Dental pulp marrow similar cells (dpmsc) and methods of isolating and using

ABSTRACT

The invention provides for isolated population of pulp marrow similar cells (DPMSCs) and methods for isolating and using these cells. The population of DPMSCs are highly homogenous for CD1O, CD29, CD13, CD44, CD49a, CD49d, CD59, CD73, CDw90, CD105, Oct-4 Isoform A and B, Nanog, Sox-2, and SSEA-4.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is related to and claims the priority benefit ofItalian patent application RM2008A000342, filed on Jun. 26, 2008, theentire contents of which are hereby incorporated by reference in itsentirety.

FIELD OF THE INVENTION

The invention relates generally to compositions and methods forisolating and using dental pulp marrow similar cells (DPMSCs).

BACKGROUND OF THE INVENTION

Organ and tissue generation from stem cells and their successivetransplantation provide possible treatments for a number of pathologies,making stem cells a central focus of research in many fields. Using stemcells for generation of organs and tissues for transplantation providesa possible therapy for diabetes, Parkinson's disease, liver disease,heart disease, and autoimmune disorders, to name a few. However, thereare at least two major problems associated with organ and tissuetransplantation. First, there is a shortage of donor organs and tissues.As few as 10 percent of the organs needed for transplant in Italy alongever become available to a recipient. See, e.g., Nord Italian Transplantprogram report 2007. According to the Nord Italian Transplant programreport, only about 1,200 of the 9,000 Italians who needed a new kidneyin 2006 received one, and that in 2006 an average of 12% of the patientsin the waiting list for a liver transplant die while waiting to receivethe suitable organ. The second major problem is the potentialincompatibility of the transplanted tissue with the immune system of therecipient. Because the donated organ or tissue is recognized by the hostimmune system as foreign, anti-rejection medications must be provided tothe patient at a significant cost, both financially and physically.

Xenotransplantation, or transplantation of tissue or organs from anotherspecies, could provide an alternative possibility to overcome theshortage of human organs and tissues. Xenotransplantation would offerthe advantage of advanced planning of the transplant, allowing the organto be harvested while still healthy and allowing the patient to undergoany possible pre-treatment prior to transplant surgery. Unfortunately,xenotransplantation does not overcome the problem of tissueincompatibility, but even exacerbates it. Furthermore, according to theCenters for Disease Control, there is evidence that damaging virusescross species barriers. Pigs have become likely candidates as organ andtissue donors, yet cross-species transmission of more than one virusfrom pigs to humans has been documented. For example, over a millionpigs were reported slaughtered in Malaysia in an effort to contain anoutbreak of Hendra virus, a disease that was transmitted to more than 70humans with deadly results. See, e.g., Butler, D., Nature (1999) 398:549.

A promising source of organs and tissues for transplantation thereforelies in the development of stem cell technology. Theoretically, stemcells can undergo self-renewing cell division to give rise tophenotypically and genotypically identical daughters for an indefinitetime and ultimately can differentiate into at least one final cell type.By generating tissues or organs from a patient's own stem cells, or bygenetically altering heterologous cells so that the recipient immunesystem does not recognize them as foreign, transplant tissues can begenerated to provide the advantages associated with xenotransplantationwithout the associated risk of infection or tissue rejection.

Stem cells also provide promise for improving the results of genetherapy. A patient's own stem cells could be genetically altered invitro, then reintroduced in vivo to produce a desired gene product.These genetically altered stem cells would have the potential to beinduced to differentiate to form a multitude of cell types forimplantation at specific sites in the body, or for systemic application.Alternatively, heterologous stem cells could be genetically altered toexpress the recipient's major histocompatibility complex (MHC) antigen,or no MHC, to allow transplant of those cells from donor to recipientwithout the associated risk of rejection.

Stem cells are cells that have extensive, possibly indefinite,proliferation potential to differentiate into several cell lineages andcan repopulate tissues upon transplantation. The quintessential stemcell is the embryonic stem (ES) cell, as it has unlimited self-renewaland multipotent differentiation potential. These cells are derived fromthe inner cell mass of the blastocyst, or can be derived from theprimordial germ cells from a post-implantation embryo (embryonal germcells or EG cells). ES and EG cells have been derived from mouse, andmore recently also from non-human primates and humans. When introducedinto mouse blastocysts or blastocysts of other animals, ES cells cancontribute to all tissues of the mouse (animal). When transplanted inpost-natal animals, ES and EG cells generate teratomas, which againdemonstrates their multipotency. ES (and EG) cells can be identified bypositive staining with the antibodies SSEA-1 and SSEA-4.

At the molecular level, ES and EG cells express a number oftranscription factors highly specific for these undifferentiated cells.These include Oct-4 and Nanog. Also found are the LIF-R and thetranscription factors Sox-2 and Rox-1, even though the latter two arealso expressed in non-ES cells. Oct-4 is a transcription factorexpressed in the pre-gastrulation embryo, early cleavage stage embryo,cells of the inner cell mass of the blastocyst, and in embryoniccarcinoma (EC) cells. Oct-4 is down-regulated when cells are induced todifferentiate in vitro and in the adult animal, Oct-4 is only found ingerm cells. Several studies have shown that Oct-4 is required formaintaining the undifferentiated phenotype of ES cells and plays a majorrole in determining early steps in embryogenesis and differentiation.Oct-4, in combination with Rox-1, causes transcriptional activation ofthe Zn-finger protein Rex-1 and is also required for maintaining ES inan undifferentiated state. Human or murine primordial germ cells requirepresence of LIF. Another hallmark of ES cells is presence of telomerase,which provides these cells with an unlimited self-renewal potential invitro.

Stem cells have been identified in most organ tissues. The bestcharacterized is the hematopoietic stem cell. This is a mesoderm-derivedcell that has been purified based on cell surface markers and functionalcharacteristics. The hematopoietic stem cell, isolated from bone marrow,blood, cord blood, fetal liver and yolk sac, is the progenitor cell thatreinitiates hematopoiesis for the life of a recipient and generatesmultiple hematopoietic lineages (see Fei, R., et al., U.S. Pat. No.5,635,387; McGlave, et al., U.S. Pat. No. 5,460,964; Simmons, P., etal., U.S. Pat. No. 5,677,136; Tsukamoto, et al., U.S. Pat. No.5,750,397; Schwartz, et al., U.S. Pat. No. 5,759,793; DiGuisto, et al.,U.S. Pat. No. 5,681,599; Tsukamoto, et al., U.S. Pat. No. 5,716,827;Hill, B., et al., Exp. Hematol. (1996) 24(8): 936-943). Whentransplanted into lethally irradiated animals or humans, hematopoieticstem cells can repopulate the erythroid, neutrophil-macrophage,megakaryocyte and lymphoid hemopoietic cell pool. In vitro, hemopoieticstem cells can be induced to undergo at least some self-renewing celldivisions and can be induced to differentiate to the same lineages as isseen in vivo. Therefore, this cell fulfills the criteria of a stem cell.Stem cells which differentiate only to form cells of hematopoieticlineage, however, are unable to provide a source of cells for repair ofother damaged tissues, for example, heart or lung tissue damaged byhigh-dose chemotherapeutic agents.

A second stem cell that has been studied extensively is the neural stemcell (Gage F. H., Science 287:1433-1438, 2000); Svendsen C. N., et al,Brain Path. 9:499-513, 1999; Okabe S., et al, Mech. Dev. 59:89-102,1996). Neural stem cells were initially identified in the subventricularzone and the olfactory bulb of fetal brain. Until recently, it wasbelieved that the adult brain no longer contained cells with stem cellpotential. However, several studies in rodents, and more recently alsonon-human primates and humans, have shown that stem cells continue to bepresent in adult brain. These stem cells can proliferate in vivo andcontinuously regenerate at least some neuronal cells in vivo. Whencultured ex vivo, neural stem cells can be induced to proliferate, aswell as to differentiate into different types of neurons and glialcells. When transplanted into the brain, neural stem cells can engraftand generate neural cells and glial cells. Therefore, this cell fallswithin the scope of a stem cell.

Mesenchymal stem cells (MSC), originally derived from the embryonalmesoderm and isolated from adult bone marrow, can differentiate to formmuscle, bone, cartilage, fat, marrow stroma, and tendon. Duringembryogenesis, the mesoderm develops into limb-bud mesoderm, tissue thatgenerates bone, cartilage, fat, skeletal muscle and possiblyendothelium. Mesoderm also differentiates to visceral mesoderm, whichcan give rise to cardiac muscle, smooth muscle, or blood islandsconsisting of endothelium and hematopoietic progenitor cells. Primitivemesodermal or mesenchymal stem cells, therefore, could provide a sourcefor a number of cell and tissue types. A third tissue specific cell thathas been named a stem cell is the mesenchymal stem cell, initiallydescribed by Fridenshtein (Fridenshtein, Arkh. Patol., 44:3-11, 1982). Anumber of mesenchymal stem cells have been isolated (see, for example,Caplan, A., et al., U.S. Pat. No. 5,486,359; Young, H., et al., U.S.Pat. No. 5,827,735; Caplan, A., et al., U.S. Pat. No. 5,811,094; Bruder,S., et al., U.S. Pat. No. 5,736,396; Caplan, A., et al., U.S. Pat. No.5,837,539; Masinovsky, B., U.S. Pat. No. 5,837,670; Pittenger, M., U.S.Pat. No. 5,827,740; Jaiswal, N., et al., J. Cell Biochem. (1997) 64(2):295-312; Cassiede P., et al., J. Bone Miner. Res. (1996) 11(9):1264-1273; Johnstone, B., et al., Exp. Cell Res. (1998) 238(1): 265-272;Yoo, et al., J. Bone Joint Sure. Am. (1998) 80(12): 1745-1757; Gronthos,S., Blood (1994) 84(12): 4164-4173; Makino, S., et al., J. Clin. Invest.(1999) 103(5): 697-705). Of the many mesenchymal stem cells that havebeen described, all have demonstrated limited differentiation to formonly those differentiated cells generally considered to be ofmesenchymal origin. To date, the most multipotent mesenchymal stem cellreported is the cell isolated by Pittenger, et al., which expresses theSH2⁺SH4⁺CD29⁺CD44⁺CD71⁺CD90⁺CD106⁺CD120a⁺CD124⁺CD14⁻CD34⁻CD45⁻phenotype. This cell is capable of differentiating to form a number ofcell types of mesenchymal origin, but has been reported by the team whoisolated it to be apparently limited in differentiation potential tocells of the mesenchymal lineage since hematopoietic cells were neveridentified in the expanded cultures. (Pittenger, et al., Science (1999)284: 143-147.)

Other stem cells have been identified, including gastrointestinal stemcells, epidermal stem cells, and hepatic stem cells, also termed ovalcells (Potten C., Philos Trans R Soc Lond B Biol Sci 353:821-30, 1998;Watt F., Philos. Trans R Soc Lond B Biol Sci 353:831, 1997; Alison M.,et al, Hepatol 29:678-83, 1998).

Compared with ES cells, tissue specific stem cells have lessself-renewal ability and, although they differentiate into multiplelineages, they are not as pluripotent. In addition, the degree oftelomerase activity in tissue specific stem cells has not been fullyexplored, in part because large numbers of highly enriched populationsof these cells are difficult to obtain.

Until recently, it was thought that organ specific stem cells could onlydifferentiate into cells of the same tissue. A number of recentpublications have suggested that adult organ specific stem cells may becapable of differentiating into cells of different tissues. A number ofstudies have shown that cells transplanted at the time of a bone marrowtransplant can differentiate into skeletal muscle (Ferrari, Science279:528-30, 1998; Gussoni, Nature 401:390-4, 1999). This could beconsidered within the realm of possible differentiation potential ofmesenchymal cells that are present in marrow. Jackson reported thatmuscle satellite cells can differentiate into hemopoietic cells, again aswitch in phenotype within the splanchnic mesoderm (Jackson, PNAS USA,96:14482-6, 1999). Other studies have shown that stem cells from oneembryonal layer (e.g., splanchnic mesoderm) can differentiate intotissues thought to be derived during embryogenesis from a differentembryonal layer. For example, endothelial cells or their precursorsdetected in humans or animals that underwent marrow transplantation areat least in part derived from the marrow donor (Takahashi, Nat Med5:434-8, 1999; Lin, Clin Invest 105:71-7, 2000). Thus, visceral mesodermand not splanchnic mesoderm, such as MSC, derived progeny aretransferred with the infused marrow. Even more surprising are thereports demonstrating both in rodents and humans that hepatic epithelialcells and biliary duct epithelial cells are derived from the donormarrow (Petersen, Science 284:1168-1170, 1999; Theise, Hepatology31:235-40, 2000; Theise, Hepatology 32:11-6, 2000). Likewise, threegroups have shown that neural stem cells can differentiate intohemopoietic cells. Finally, Clarke et al. reported that neural stemcells injected into blastocysts can contribute to all tissues of thechimeric mouse (Clarke, Science 288:1660-3, 2000).

Many of these studies have not conclusively demonstrated that a singlecell can differentiate into tissues of different organs. Manyinvestigators did not identify the phenotype of the initiating cell. Anexception is the study by Weissman and Grompe, who showed that cellsthat repopulated the liver were present in Lin⁻Thy_(tLow)Sca₁₊ marrowcells, which are highly enriched in hematopoietic stem cells. Likewise,the Mulligan group showed that marrow Sp cells, highly enriched for HSC,can differentiate into muscle and endothelium, and Jackson et al. showedthat muscle Sp cells are responsible for hemopoietic reconstitution(Gussoni et al., Nature 401:390-4, 1999).

Transplantation of tissues and organs generated from heterologousembryonic stem cells requires either that the cells be furthergenetically modified to inhibit expression of certain cell surfacemarkers, or that the use of chemotherapeutic immune suppressors continuein order to protect against transplant rejection. Thus, althoughembryonic stem cell research provides a promising alternative solutionto the problem of a limited supply of organs for transplantation, theproblems and risks associated with the need for immunosuppression tosustain transplantation of heterologous cells or tissue would remain. Anestimated 20 immunologically different lines of embryonic stem cellswould need to be established in order to provide immunocompatible cellsfor therapies directed to the majority of the population (Wadman, M.,Nature (1999) 398: 551).

Using cells from the developed individual, rather than an embryo, as asource of autologous or allogeneic stem cells would overcome the problemof tissue incompatibility associated with the use of transplantedembryonic stem cells, as well as solve the ethical dilemma associatedwith embryonic stem cell research. The greatest disadvantage associatedwith the use of autologous stem cells for tissue transplant thus farlies in their limited differentiation potential. A number of stem cellshave been isolated from fully-developed organisms, particularly humans,but these cells, although reported to be pluripotent, have demonstratedlimited potential to differentiate to multiple cell types.

Thus, even though stem cells with multiple differentiation potentialhave been isolated previously by others and by the present inventors, aprogenitor cell with the potential to differentiate into a wide varietyof cell types of different lineages, including fibroblasts, osteoblasts,chondrocytes, adipocytes, skeletal muscle, endothelium, stroma, smoothmuscle, cardiac muscle and hemapoietic cells, has not been described. Ifcell and tissue transplant and gene therapy are to provide thetherapeutic advances expected, a stem cell or progenitor cell with thegreatest or most extensive differentiation potential is needed. What isneeded is the adult equivalent of an embryonic stem cell.

As an alternative to embryonic stem cell therapy, adult stem cells haveshown promise (Caplan, 1991, 2000, 2003, 2004, 2005; Caplan and Bruder,2001; Kuehle and Goodell, 2002; Pittenger, 2004). For example,multipotent adult progenitor cells from mouse bone marrow (mMAPC) wereshown to express several embryonic stem (ES) cell markers, such as Oct-4(POU transcription factor), Rex-1 (transcription factor) and SSEA-1(stage-specific embryonic antigen), and to contribute to all embryoniccell lineages when a single cell is injected into the blastocyst (Jianget al., 2002). While bone marrow is an excellent source of stem cellswith proven therapeutic value, the process of collecting bone marrow isinvasive, and, moreover, recent data implicate bone marrow stem cells incancer development (Houghton et al., 2004). The expansion of the list ofthe potential sources of pluripotent adult stem cells beyond a smallgroup consisting of cord blood, bone marrow, adipose tissue, andamniotic stem cells (Jiang et al., 2002; Zuk et al., 2002; Miki et al.,2005) would be of value. Extending earlier findings in rodents (Mann etal., 1996), the recent discovery of relatively immature stem cells inthe dental pulp of human exfoliated deciduous teeth (SHED) has offered apotentially non-invasive source of stem cells (Miura et al., 2003). SHEDshowed rapid expansion and proliferation in vitro while expressingseveral mesenchymal stem cell markers, such as STRO-1 and CD146. Stemcells from dental pulp (Miura et al., 2003) appeared to be inferior intheir potential therapeutic value compared to ES cells or mMAPCs, sincethey were not shown to express Oct-4, SSEAs, Nanog, or any otherhallmarks of totipotent stem cells, while their multilineage terminaldifferentiation was only marginally successful (Jiang et al., 2002;Chambers et al., 2003; Constantinescu, 2003; Laslett et al., 2003;Mitsui et al., 2003; Pierdomenico et al., 2005; Laino et al., 2006).SHED have been shown to be highly heterogeneous, because only 9% of SHEDexpress markers of undifferentiated cells, and it is not clear if clonesobtained from SHED maintain expression of these markers (Miura et al.,2003). Previously, it has been reported that removal of stem cells fromtheir natural milieu may change their differentiation properties(Bissell and Lafarge, 2005; Schwartz and Verfaillie, 2005). Additionalpublications that described stem cells obtained from dental pulpinclude: WO 03/066840, WO 04/094588, US 2005/0106724, US 2007/0009492,US 2007/0258957, WO 03/066840, EP 1748066 A1, WO 2006/010600, and WO2006/100088. However, none of these references describe a homogeneouspopulation of purified stem cells which can differentiate into cells ofdifferent lineages.

Accordingly, what is needed is a population of stem cells which show theplasticity of ES cells in their ability to become a multitude of cellsbut derived from non-embryonic sources and non-invasive sources. Thepresent invention fulfils these needs and provides additional benefitsas well.

The specification is most thoroughly understood in light of thereferences cited herein. Some of the references have their fullbibliographic information after the Examples section. The disclosures ofall publications, patents, patent applications, and published patentapplications referred to herein are each hereby incorporated byreference herein in their entireties.

SUMMARY OF THE INVENTION

The invention provides for compositions of isolated dental pulp marrowsimilar cells (DPMSC) and methods of isolating, culturing, anddifferentiating these cells as well as methods for using these cells.The isolated populations of DPMSCs display particular marker phenotype,which can be measured by protein analysis or nucleic acid analysis(e.g., rt-PCR). Accordingly, in one aspect, the invention provides foran isolated population of DPMSCs wherein at least about 90% of the cellsin the population co-express each of the following markers: CD10, CD13,CD29, CD44, CD49a, CD49d, CD59, CD73, CD90, CD105, Oct-4 Isoform A andB, Nanog, Sox-2, and SSEA-4. In another aspect, the invention providesfor an isolated population of DPMSCs wherein at least about 95% of thecells in the population co-express each of the following markers: CD10,CD13, CD29, CD44, CD49a, CD49d, CD59, CD73, CD90, CD105, Oct-4 Isoform Aand B, Nanog, Sox-2, and SSEA-4. In another aspect, the inventionprovides for an isolated population of DPMSCs wherein about 90-99% ofthe cell population expresses each of the following markers: CD10, CD13,CD29, CD44, CD49a, CD49d, CD59, CD73, CD90, CD105, Oct-4 Isoform A andB, Nanog, Sox-2, and SSEA-4.

In another aspect, any of the populations of DPMSCs can exhibit thephenotype wherein 0.25-1% of the cells in the population express CD34and CD45. In another aspect, any of the populations of DPMSCs canexhibit the phenotype wherein less than 1% of the cells in thepopulation express CD34 and CD45. In another aspect, any of thepopulations of DPMSCs can exhibit the phenotype wherein the cells of thepopulation co-express mRNA of each of the following: Oct-4 Isoforms Aand B, Nanog, Sox-2, SSEA-4, c-Myc, Klf-4, and Rex-1. In another aspect,any of the populations of DPMSCs can exhibit the phenotype wherein thepopulation has an average doubling rate of about 28-30 hours. In anotheraspect, any of the populations of DPMSCs can exhibit the phenotypewherein the DPMSCs have the capacity to differentiate into one, two orall three of the cell types of ectodermal, endodermal, or mesodermallineages. In another aspect, any of the populations of DPMSCs can behuman DPMSCs.

The invention also provides for isolated populations of DPMSCs derivedfrom human dental pulp, wherein at least about 90% of the cells in thepopulation co-express each of the following markers: CD10, CD29, CD13,CD44, CD49a, CD49d, CD59, CD73, CDw90, CD105, Oct-4, Nanog, Sox-2, andSSEA-4; wherein 0.25-1% of the cells in the population express CD34 andCD45; wherein the cells have normal karyotype; and wherein the cells ofthe population have the capacity to differentiate into cell types of atleast two of ectodermal, endodermal, or mesodermal lineages.

In another aspect, any of the population of DPMSCs can exhibit thephenotype wherein the cells have the capacity to differentiate into anyone or more of the following: osteoblast, skeletal muscle cell, smoothmuscle cell, cardiac muscle cell, glial cell, and neuronal cell.

In some aspects, the DPMSCs are derived from a tooth organ. In oneaspect, the tooth organ is from a child. In another aspect, the toothorgan is from an adult.

In some aspects, the population of DPMSCs is contained in a vessel, suchas tissue culture plates, bottles and matrices.

The invention also provides for isolated populations of DPMSCs whichhave been cultured to induce differentiation wherein the startingpopulation is DPMSCs described above, wherein the differentiationresults in the DPMSC becoming a differentiated cell selected from agroup consisting of: a bone cell, skeletal muscle cell, smooth musclecell, cardiac muscle cell, glial cell, neuronal cell, skin epithelialcell, liver epithelial cell, pancreas epithelial cell, pancreasendocrine cell, pancreatic islet cell, pancreas exocrine cell, gutepithelium cell, kidney epithelium cell, epidermal associated structure,hair follicles, soft tissues surrounding teeth, dentin (teeth), enamel(teeth), and cement (teeth).

The invention also provides for isolated populations of DPMSCs whereinthe genome of the cells in the population has not been altered byinsertion of pre-selected isolated DNA, by substitution of a segment ofthe cellular genome with pre-selected isolated DNA, or by deletion of orinactivation of at least a portion of the cellular genome.

The invention also provides for methods of obtaining a population ofDPMSCs described above by culturing a dental pulp source in mediasupplemented with one or more growth factors selected from the groupconsisting of: platelet-derived growth factor, insulin, selenium,epidermal growth factor (EGF), insulin-like growth factor (IGF),dexamethasone, linoleic acid, and ascorbic acid to obtain population ofDPMSCs. In some aspects, all of the previous components are included inthe culturing media. In some aspects, the DPMSCs are human DPMSCs andthe dental pulp source is from a human In other aspects, the adherentcells and non-adherent cells are co-cultured without selection byimmunodepletion, physical depletion, or chemical depletion. In otheraspects, the method does not deplete the starting source of cells or thecell culture of mononuclear cells expressing CD3, CD14, CD19, CD38,CD66b and CD45 glycophorin A. In other aspects, the methods furthercomprise placing the cells in a cell culture container, wherein the cellculture container does not comprises an extracellular matrix (ECM)substrate. In other aspects of the methods, the serum percentagecomprises about 0.5-2.5%.

In another aspect of the invention, the methods of culturing include oneor more of the following culturing parameters: insulin is present at aconcentration of about 10 to about 50 μg/ml, transferrin at aconcentration of greater than 0 but less than about 10 μg/ml, seleniumat a concentration of about 0.1 to about 5 μg/ml, linoleic acid at aconcentration of about 0 to about 1 μg/m, dexamethasone at aconcentration of about 0.005 to 0.15 μM, L-ascorbic acid at aconcentration of about 10-50 mg/L, platelet-derived growth factor at aconcentration of about 5 to about 15 ng/ml, epidermal growth factor 1 toat a concentration of about 15 ng/ml, insulin-like growth factor at aconcentration of 1 to about 15 ng/ml, and fibroblast growth factor-b1 ata concentration of about 15 ng/ml. In yet another aspect, the methods ofculturing include all of previous components in the culturing media.

In another aspect, the invention provides for methods of inducingdifferentiation of DPMSCs to differentiated cells and compositions ofthe differentiated cells obtained from these methods.

The invention also encompasses cells produced by any of the processesdescribed herein. In one embodiment, the invention provides for DPMSCsproduced by the culturing method as described in Example 1.

In another aspect, the invention provides for methods of providingtherapeutic assistance to an individual in need thereof by administeringan amount of DPMSCs effective to aid therapy to the individual. Inanother aspect, the invention provides for methods of administering stemcells to an individual in need thereof for beneficial effects. In someembodiments, an effective amount of cells are introduced to theindividual in need thereof. In other embodiments, the individual in needthereof is an individual with any one or more of the medical,biological, genetic or physiological conditions described herein.

In yet another aspect, the invention provides methods of providingtherapeutic enzymes, proteins, or other biological product to anindividual with or suspected of having a genetic defect by:

(a) performing an in utero transplantation of a sufficient amount ofDPMSCs to form a chimerism of cells or tissues to produce human cells inprenatal or post-natal individuals following transplantation and (b)allowing the cells to produce therapeutic enzymes, proteins, or otherproducts in the individual with or suspected of having genetic defects.

In yet another aspect, the invention provides methods of providing genetherapy in an individual in need of therapeutic treatment, by: (a)genetically altering DPMSCs by introducing an isolated pre-selected DNAencoding a desired gene product into one or more DPMSCs; (b) expandingthe cells in culture; and (c) introducing the cells into the body of theindividual to produce the desired gene product, thus providing genetherapy.

In yet another aspect, the invention provides methods of providingtherapy for damaged tissue in a human individual in need thereof by: (a)culturing the DPMSCs to proliferate them; and (b) contacting aneffective amount of the expanded DPMSCs with the damaged tissue of saidindividual to provide therapy. In one embodiment, the cells areintroduced into the body of the individual by localized injection or bysystemic injection. In another embodiment, the cells are introduced intothe body of the individual in conjunction with a suitable matrix implantthat provides additional genetic material, cytokines, growth factors, orother factors to promote growth and differentiation of the cells. Inanother embodiment, the cells are encapsulated within a polymer capsuleprior to introduction into the body of the individual.

In yet another aspect, the invention provides methods of identifyinggenetic polymorphisms associated with physiologic abnormalities by: (a)isolating DPMSCs from a statistically significant population ofindividuals from whom phenotypic data can be obtained; (b) expanding theDPMSCs from the statistically significant population of individuals toestablish DPMSC cultures; (c) identifying at least one geneticpolymorphism in the cultured DPMSCs; (d) inducing the cultured DPMSCs todifferentiate; and (e) characterizing aberrant metabolic processesassociated with the genetic polymorphism by comparing thedifferentiation pattern exhibited by DPMSCs having a normal genotypewith the differentiation pattern exhibited by DPMSCs having anidentified genetic polymorphism.

In yet another aspect, the invention provides methods for treatingcancer in an individual in need thereof by: (a) genetically alteringDPMSCs to express a tumoricidal protein, an anti-angiogenic protein, ora protein that is expressed on the surface of a cancer cell inconjunction with a protein associated with stimulation of an immuneresponse to antigen; and (b) introducing an amount of the geneticallyaltered DPMSCs into the individual effective to halt the growth of oreradicate the cancer cells.

In yet another aspect, the invention provides methods of determiningcellular responses to biologic or pharmacologic agents by: (a) isolatingDPMSCs from a statistically significant population of individuals; (b)expanding the DPMSCs from the statistically significant population ofindividuals to establish a plurality of DPMSC cultures; (c) contactingthe DPMSC cultures with one or more biologic or pharmacologic agents;(d) identifying one or more cellular responses to the one or morebiologic or pharmacologic agents; and (e) comparing the cellularresponses of the DPMSC cultures from individuals in the statisticallysignificant population to determine the cellular responses to biologicor pharmacologic agents.

In yet another aspect, the invention provides methods of treatingblindness in an individual in need thereof comprising administering toindividual an effective amount of neuroretinal cells derived fromDPMSCs. In one embodiment, the blindness is associated with any one ormore of the following: neuroretinal disease, macular degeneration,diabetic retinopathy, glaucoma, or retinitis pigmentosa. In anotherembodiment, the DPMSC is genetically modified to selectively express anendogenous gene or a transgene that ameliorates blindness in theindividual.

In yet another aspect, the invention provides methods for treatingperiodontal disease in an individual in need thereof comprisingadministering to the individual an effective amount of gingiva-likematerial wherein the gingiva-like material has been derived from DPMSCs.

In yet another aspect, the invention provides methods for aiding skingrafting and plastic surgery in an individual in need thereof comprisingadministering to the individual an effective amount of skin epithelialtissue wherein the skin epithelial tissue has been derived from DPMSCs.

In yet another aspect, the invention provides methods for producinghuman hematopoietic cells or blood cells ex vivo comprising culturingDPMSCs in a manner as to induce its differentiation into hematopoieticcells or blood cells.

In yet another aspect, the invention provides methods for providingtherapeutic assistance to treat cardiac diseases in an individual inneed thereof comprising administering to the individual an amount ofcardiomyocytes derived from DPMSCs effective to ameliorate cardiacfailure. In some embodiments, the cardiac disease is selected from thegroup consisting of: myocarditis, cardiomyopathy, heart failure, damagecaused by heart attacks, hypertension, atherosclerosis, and heart valvedysfunction.

In yet another aspect, the invention provides methods for providingtherapeutic assistance to treat neural diseases in an individual in needthereof comprising administering to the individual an amount of DPMSCsor neuronally related differentiated cells derived from DPMSCs effectiveto aid amelioration of neurodegenerative diseases. In some embodiments,the neural disease is selected from the group consisting of: stroke,Alzheimer's, Parkinson's disease, Huntington's disease, AIDS associateddementia, spinal cord injury, and metabolic diseases affecting the brainor other nerves.

In yet another aspect, the invention provides methods for providingtherapeutic assistance to treat diseases of the joints or cartilage inan individual in need thereof comprising administering to the individualan amount of DPMSCs, chondrocytes derived from DPMSCs, or osteoblastderived from DPMSCs effective to aid amelioration of cartilagedegenerative diseases. In some embodiments, the disease of the joints orcartilage is selected from the group consisting of: cartilage tears,cartilage thinning, osteoarthritis, bone fractures, non-healingfractures, osteoarthritis, and holes in bones cause by cancerous tumorsspreading to bone.

In yet another aspect, the invention provides methods of providing adatabase of gene profiles of a pluripotent derived stem cell to aid indrug discovery by: (a) determining the gene profile from DPMSCs from atleast one individual, wherein the gene profile involves at least onegene; and (b) storing the gene profile(s) on an accessible medium.

DETAILED DESCRIPTION

The invention provides for compositions, methods for isolation ofDPMSCs, methods for inducing specific differentiation of the cells andthe cell populations resulting therefrom. More specifically, theinvention relates to an isolated population of DPMSCs, which is highlyhomogeneous such that a significant percentage, or proportion of, thepopulation of DPMSCs co-expresses the following markers: CD10, CD13,CD29, CD44, CD49a, CD49d, CD59, CD73, CDw90, CD105, Oct-4 Isoform A andB, Nanog, Sox-2, and SSEA-4 and such that, within the same population, alow percentage of the cells in the population express CD34 and CD45. Thehighly homogeneous population of DPMSCs have the potential todifferentiate to form cells of a variety of cell lineages of theendoderm, mesoderm, and ectoderm.

I. GENERAL TECHNIQUES

The practice of the present invention will employ, unless otherwiseindicated, conventional techniques of stem cell biology, cell culturing,molecular biology (including recombinant techniques), microbiology, cellbiology, biochemistry and immunology, which are within the skill of theart. Such techniques are explained fully in the literature, such as,Molecular Cloning: A Laboratory Manual, third edition (Sambrook et al.,2001) Cold Spring Harbor Press; Oligonucleotide Synthesis (P. Herdewijn,ed., 2004); Animal Cell Culture (R. I. Freshney), ed., 1987); Methods inEnzymology (Academic Press, Inc.); Handbook of Experimental Immunology(D. M. Weir &C. C. Blackwell, eds.); Gene Transfer Vectors for MammalianCells (J. M. Miller & M. P. Calos, eds., 1987); Current Protocols inMolecular Biology (F. M. Ausubel et al., eds., 1987); PCR: ThePolymerase Chain Reaction, (Mullis et al., eds., 1994); CurrentProtocols in Immunology (J. E. Coligan et al., eds., 1991) ShortProtocols in Molecular Biology (Wiley and Sons, 1999), Embryonic StemCells: A Practical Approach (Notaranni et al. eds., Oxford UniversityPress 2006); Essentials of Stem Cell Biology (R. Lanza, ed., ElsevierAcademic Press 2006); Stem Cell Assays (Methods in Molecular Biology)(Mohan C. Vemuri, Ed., Humana Press; first edition (Aug. 10, 2007);Mesenchymal Stem Cells: Methods and Protocols (Methods in MolecularBiology) (Darwin J. Prockop, Donald G. Phinney, Bruce A. Bunnell, Eds.,first edition (Mar. 7, 2008)); Handbook of Stem Cells (Robert Lanza, etal., Eds., Academic Press (Sep. 14, 2004); Stem Cell Culture Vol 86:Methods in Cell Biology (Jennie P. Mather, Ed., Academic Press, firstedition (May 15, 2008)); Practical Hematopoietic Stem CellTransplantation (Andrew J. Cant, et al. Eds., Wiley-Blackwell, firstedition (Jan. 22, 2007)); Hematopoietic Stem Cell Protocols (Kevin D.Bunting, Ed., Humana Press, 2nd ed. edition (Jan. 31, 2008)); BoneMarrow and Stem Cell Transplantation (Methods in Molecular Medicine)(Meral Beksac, Ed., Humana Press; first edition (May 3, 2007)); StemCell Therapy and Tissue Engineering for Cardiovascular Repair From BasicResearch to Clinical Applications (Nabil Dib, et al., Eds., Springer,first edition (Nov. 16, 2005)); Blood And Marrow Stem CellTransplantation: Principles, Practice, And Nursing Insights (KimSchmit-Pokorny (Author) and Susan Ezzone (Editor), Jones & BartlettPublishers; third edition (May 22, 2006)); Hematopoietic Stem CellProtocols (Christopher A. Klug and Craig T. Jordan, Eds., Humana Press;first edition (Dec. 15, 2001)); and Clinical Bone Marrow and Blood StemCell Transplantation (Kerry Atkinson, et al., Eds., Cambridge UniversityPress; third edition (Dec. 8, 2003)).

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as is commonly understood by one of ordinary skillin the art to which this invention belongs.

If a definition set forth in this section is contrary to or otherwiseinconsistent with a definition set forth in patents, published patentapplications and other publications that are herein incorporated byreference, the definition set forth in this section prevails over thedefinition that is incorporated herein by reference.

II. DEFINITIONS

As used herein, the terms “dental pulp-derived stem cell (DPSC),”“dental pulp-derived progenitor cells,” “dental pulp marrow similarcells” (DPMSC), are used interchangeably and refer to a highlyhomogeneous cell population that is fairly uniform in its co-expressionof a panel of certain markers: CD10, CD13, CD29, CD44, CD49a, CD49d,CD59, CD73, CDw90, CD105, Oct-4 Isoform A and B, Nanog, Sox-2, SSEA-4,CD34, and CD45. It is to be understood that other markers can beexpressed on the DPMSCs in addition to the list above.

As used herein, the terms “highly homogenous” and “homogenous”population of DPMSCs refer to a population of DPMSCs that is fairlyuniform in its co-expression of a panel of certain markers: CD10, CD13,CD29, CD44, CD49a, CD49d, CD59, CD73, CDw90, CD105, Oct-4 Isoform A andB, Nanog, Sox-2, SSEA-4, CD34, and CD45. In one aspect, a significantpercentage, or proportion of the population of DPMSCs of the inventionexpress the following markers: CD10, CD13, CD29, CD44, CD49a, CD49d,CD59, CD73, CDw90, CD105, Oct-4 Isoform A and B, Nanog, Sox-2, andSSEA-4 and additionally, within the same population, a low percentage ofthe cells in the population express CD34 and CD45. The percentage of thepopulation of DPSMCs co-expressing the marker profiles described hereincan be about any of about 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%,98%, or 99%. In some aspects, the percentage of the population of DPSMCsco-expressing the marker profiles described herein can be at least aboutany of about 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 98%, or 99%.The population of DPMSCs can be contained in a vessel for purposes ofculturing, proliferation, or differentiation, which encompasses not onlystandard cell culture vessels but matrices and other materials withwhich one of skill in the art would use to culture DPMSCs.

As used herein, the term “population” or “isolated population” ofpluripotent DPMSCs refers to a population of one or more DPMSCs that hasbeen manipulated to provide a preparation of cells that is substantiallyfree of additional components. In some aspects, the cell preparation isat least about 60%, by weight, volume, or number, free from othercomponents that are present when the cell is produced or cultured. Invarious aspects, the cell is at least about 75%, or at least about 85%,or at least about 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, or at leastabout 98%, or at least about 99%, by weight, volume, or number, pure. Insome aspects, the percentage refers to a percentage of stem cells in acell culture or population. A population or isolated population ofDPMSCs can be obtained, for example, by purification from a naturalsource, e.g., by mechanical or physical or chemical extraction,fluorescence-activated cell-sorting, or other techniques known to theskilled artisan. The purity can be assayed by any appropriate method,such as fluorescence-activated cell-sorting (FACS) or by visualexamination.

“Purity” as used to describe the purity of stem cells does not refer tothe presence of only stem cells in the composition but rather indicatesthat the stem cells have been manipulated such that they have beenremoved from their natural tissue environment and indicates theirrelationship to the other cells present in the resulting population.

As used herein, the term “pluripotent” refers to a DPMSC's potential todifferentiate into cells of the three germ layers: endoderm (e.g.,interior stomach lining, gastrointestinal tract, the lungs), mesoderm(e.g., muscle, bone, blood, urogenital), or ectoderm (e.g., epidermaltissues and nervous system). Pluripotent stem cells can give rise to anyfetal or adult cell type. Alone, they cannot develop into a fetal oradult animal because they lack the potential to contribute toextraembryonic tissue (e.g., placenta in vivo or trophoblast in vitro).

An “individual,” “subject” or “patient” is a vertebrate. In certainembodiments, the vertebrate is a mammal Mammals include, but are notlimited to, primates (including human and non-human primates), pets(e.g., dogs, cats, rabbits, etc.), agricultural animals (e.g., cows,livestock, etc.), sport animals (e.g., horses), and rodents (e.g., miceand rats). In certain embodiments, a mammal is a human.

By “treatment” or “treating” is meant an approach for obtaining abeneficial or desired result, including clinical results. For purposesof this invention, beneficial or desired results include, but are notlimited to, alleviation of symptoms associated with a conditiondiminishment of the extent of one or more symptoms associated with acondition, or prevention of a worsening of the symptoms associated witha condition. In some aspects, treatment with a one or more cellsdisclosed herein is accompanied by no or fewer side effects than areassociated with currently available therapies.

“Receiving treatment” includes initial treatment and/or continuingtreatment.

As used herein, “delaying” development of a disease or condition meansto defer, hinder, slow, retard, stabilize and/or postpone development ofthe disease or condition. This delay can be of varying lengths of time,depending on the history of the disease and/or individual being treated.As is evident to one skilled in the art, a sufficient or significantdelay can, in effect, encompass prevention, in that the individual doesnot develop the disease or condition. For example, the method may reducethe probability of disease development in a given time frame and/orreduce the extent of the disease in a given time frame, when compared tonot using the method. In some aspects, such comparisons are based onclinical studies using a statistically significant number ofindividuals. Disease development can be detectable using standardclinical techniques. Development may also refer to disease progressionthat can be initially undetectable and includes occurrence, recurrence,and onset.

An “effective amount” (when used in the treatment or prophylaxiscontext, or in the context of palliating pain or alleviating thesymptoms of a particular condition) is an amount sufficient to effectbeneficial or desired results including clinical results. An effectiveamount can be administered in one or more administrations. For purposesof this invention, an effective amount of DPMSCs is a certain amount ofcells that can reduce one of more symptoms of the conditions for whichthe individual is being treated. An effective amount of DPMSCsencompasses the use of DMPSCs when they are being grown or proliferatedin their pluripotent, undifferentiated state as well as the use ofDMPSCs when they have been cultured further to induce them todifferentiate down a particular pathway (e.g., neural, cardiomyocyte,chondrocyte, etc.). When used in the context of “assisting therapy,” aneffective amount enhances a therapeutic regimen (as compared to aregimen lacking the DPMSCs) and, as such, provides a beneficial ordesired result.

As used herein, “in need thereof” includes individuals who have acondition or disease or are “at risk” for the condition or disease. Asused herein, an “at risk” individual is an individual who is at risk ofdevelopment of a condition. An individual “at risk” may or may not havea detectable disease or condition, and may or may not have displayeddetectable disease prior to the treatment methods described herein. “Atrisk” denotes that an individual has one or more so-called risk factors,which are measurable parameters that correlate with development of adisease or condition and are known in the art. An individual having oneor more of these risk factors has a higher probability of developing thedisease or condition than an individual without these risk factor(s).These risk factors include, but are not limited to, age, sex, diet,history of previous disease, presence of precursor disease, genetic(i.e., hereditary) considerations, breeding protocols andconsiderations, and environmental exposure.

By “pharmaceutically acceptable carrier” is meant any material which,when combined with an active ingredient, allows the ingredient to retainbiological activity and does not provoke an unacceptable immune response(e.g., a severe allergy or anaphylactic shock) based on the knowledge ofa skilled practitioner. Examples include, but are not limited to, any ofthe standard pharmaceutical carriers such as carboxymethylcellulose(CMC), phosphate buffered saline solutions, water, emulsions such asoil/water emulsion, and various types of wetting agents. Exemplarydiluents for aerosol or parenteral administration are phosphate bufferedsaline or normal (0.9%) saline. An exemplary carrier for the infusion ofcells is CMC. Compositions comprising such carriers are formulated bywell known conventional methods (see, for example, Remington'sPharmaceutical Sciences, 18th edition, A. Gennaro, ed., Mack PublishingCo., Easton, Pa., 1990; and Remington, The Science and Practice ofPharmacy 20th Ed. Mack Publishing, 2000, which are each herebyincorporated by reference in their entireties, particularly with respectto formulations).

General reference to “the composition” or “compositions” includes and isapplicable to compositions of the invention. The invention also providespharmaceutical compositions comprising the components described herein.

As used herein, the singular form “a”, “an”, and “the” includes pluralreferences unless indicated otherwise. For example, “a” DPMSC includesone or more dental pulp marrow similar cells.

Reference to “about” a value or parameter herein includes (anddescribes) aspects that are directed to that value or parameter per se.For example, description referring to “about X” includes description of“X.”

It is understood that aspects and aspects of the invention describedherein include “comprising,” “consisting,” and “consisting essentiallyof” aspects and aspects.

III. POPULATION OF DENTAL PULP MARROW SIMILAR CELLS (DPMSCS)

The present invention provides for homogeneous populations of dentalpulp marrow similar cells (DPMSCs) that can differentiate to into manytypes of cells from multiple layers (e.g., ectoderm, mesoderm andendoderm). These cells show great plasticity in their ability todifferentiate into multiple types of cells from different layers of thebody. The DPMSCs exhibit differentiation phenotypes akin to an embryonicstem cell. The cells of the present invention described herein have thecapacity to differentiate to form at least one, two or threedifferentiated cell types of mesodermal, ectodermal and endodermalorigin. The phenotype of the population of DPMSCs of the invention ismore homogenous in terms of the relatively high percentage of the cellpopulation expressing particular markers (or low percentage of the cellpopulation not expressing other particular markers) than other stem cellcultures described in the art, which tended to be fairly heterogeneousin that, as a whole, those stem cell population displayed a widevariations of phenotypes.

A. DPMSCs from Dental Pulp

DPMSCs can be obtained by using a starting source of dental pulp forculturing. In one aspect of the invention, the source of the dental pulpmay be from child (e.g., teeth lost as part of losing baby teeth). Inanother aspect of the invention, the source of the dental pulp may befrom adult teeth grown after losing baby teeth. In another aspect, thestarting source may be derived from a tooth organ. In one aspect,deciduous dental pulp mononuclear cells are derived from dental pulp.

DPMSCs of the invention can be obtained from any vertebrate. In oneaspect of the invention, DPSMCs are obtained from a mammal, such as ahuman. In other aspects of the invention, the DPMSCs are obtained from anon-human. In yet other aspects of the invention, the DPMSCs areobtained from primates (including human and non-human primates), pets(e.g., dogs, cats, rabbits, etc.), agricultural animals (e.g., cows,livestock, etc.), sport animals (e.g., horses), and rodents (e.g., miceand rats). In all cases, no human embryos are destroyed in the processof obtaining DPMSCs of the invention.

Accordingly, the invention provides for compositions (e.g., populationor isolated population) of human DPMSCs, non-human DPMSCs, primateDPMSCs, as well as DPMSCs from different animal species. In one aspectof the invention, DPMSCs can be a subpopulation of dental pulp suchthat, under the experimental conditions described herein, the DPMSCs arepredominantly and selectively proliferating. In other aspects of theinvention, a gradient between the piece of dental pulp and the culturemedium can serve as a vector directing the cells toward what theyperceive as a site of injury, which can lead to their continued andselective migration in the Petri dish.

B. Phenotype of DPMSCs

The population of DPMSCs of invention can be described by variousphenotypes. In one aspect, the population of DPMSCs can be described interms of its homogeneity in its co-expression of certain markers. Thesemarkers can be on the cell surface and detected by standard methods inthe art (e.g., flow cytometry). Alternatively, the population of DPMSCscan be described by the expression of certain genes within the cells andmeasured by standard assays in the art (e.g., rt-PCR). In yet anotheralternative, the DPMSCs can also be described by its karyotype (e.g.,normal karyotype) or by its biological characteristics. Non-limitingexamples of biological activities include cell doubling time, telomeraseactivity, and differentiation capabilities.

In one aspect of the invention, DNA content can be measured by standardassays in the art (e.g., FISH). The detection of telomerase activity canbe determined by standard assays in the art (e.g., TRAP-assay/TRAPezekit). In another aspect of the invention, cells can be stained bystandard assays in the art (e.g., Von Kossa, Nuclear Fast Red). Alkalinephosphatase activity can be measured by standard assays in the art(e.g., Alkaline Phosphatase staining). In yet another aspect of theinvention, glycogen can be detected by standard assays in the art (e.g.,Periodic acid-Schiff staining). Albumin concentration can be determinedby standard assays in the art (e.g., ELISA) and urea concentration canbe determined by standary assays in the art (e.g., QuantiChrom™ UreaAssay). The details of the standard assays described here can be foundin Example 2.

Accordingly, in one aspect, the population of DPMSCs of the invention ishomogeneous in its co-expression of markers such as, but not limited to,CD10, CD13, CD29, CD44, CD49a, CD49d, CD59, CD73, CD90, CD105, Oct-4Isoform A and B, Nanog, Sox-2, and SSEA-4. Homogeneity refers to thepercentage of cells within a given population of DPMSCs that express thesame marker profile. In some aspects, the invention provides for apopulation of DPMSCs that is homogeneous in that about 40%, 50%, 60%,70%, 75%, 80%, 85%, 90%, 95%, 98%, or 99% of the cells in the populationco-express CD10, CD13, CD29, CD44, CD49a, CD49d, CD59, CD73, CD90,CD105, Oct-4 Isoform A and B, Nanog, Sox-2, and SSEA-4. In otheraspects, the invention provides for a population of DPMSCs that ishomogeneous in that at least about 40% of the cells in the populationco-express CD10, CD13, CD29, CD44, CD49a, CD49d, CD59, CD73, CD90,CD105, Oct-4 Isoform A and B, Nanog, Sox-2, and SSEA-4. Preferably, thepopulation of DPMSCs are homogeneous to the extent that at least about50%, at least about 60%, at least about 70%, at least about 75%, atleast about 80%, at least about 85%, at least about 90%, at least about95%, at least about 98%, or at least about 99% of the DPMSCs in thepopulation co-express CD10, CD13, CD29, CD44, CD49a, CD49d, CD59, CD73,CD90, CD105, Oct-4 Isoform A and B, Nanog, Sox-2, and SSEA-4. In otheraspects, about 90-99% the population of DPMSCs co-express these markers.

In another aspect, a low percentage (e.g., <1%) of the cells in thepopulation of DPMSCs exhibits expression of markers such as CD34 andCD45. In the same homogeneous population where a significant percentageor proportion (e.g., at least about 90%) of the population of DPMSCsco-express CD10, CD13, CD29, CD44, CD49a, CD49d, CD59, CD73, CD90,CD105, Oct-4 Isoform A and B, Nanog, Sox-2, and SSEA-4, a low percentageor proportion (e.g., 0.25%-1%) of the population of human DPMSCsobtained after 14-20 cell doublings has expression of CD34 and CD45. Inanother aspect of the invention, a low percentage of the cells in thepopulation of DPMSCs express CD66e, KDR, CD133, VE-Cad and CD117.

The findings by the inventors that the DPMSC population expressed SSEA-4is consistent with other immunhistochemistry and cytofluorimetricassays, which showed that human DPMSCs, grown at 2-10³/cm² seedingdensity, express SSEA-4 protein after thawed (Kannagi R, EMBO J.2:2355-61, 1983).

In another aspect of the invention, the population of DPMSCs alsoexpressed a certain profile of messenger RNA expression. Analysis of apopulation of DPMSCs by rt-PCR can be done to determine messengerexpression during proliferation phase. Non-limiting examples ofmessenger expression which can be detected in the DPMSC population ofthe invention include: Oct-4, MDR-1, Abcg-2, Msx-2, PPAR-γ, c-Met,CK-19, alkaline phosphtase, osteocalcin, osteonectin, BMP-2, BMP-4,BMP-7, BMPr-Ia, BMPr-Ib, Cbfa-I type I, Cbfa-I type II, Dlx-5, collagenI, FGFr-I, FGFr-II, aggrecan, dermo-I, dental matrix protein, G-Fap,glypican, β³-Tubulin, neurofilament light, medium, heavy, NSE, musashi,vimentin, N-nos, ASA, SMA, cardiac actin, myocardin, ANP, Gata-4,Nkx-2.5, Mef-2a, c-TnI, and myosin heavy chain. On the other hand, thepopulation of DPMSCs express minimal levels to no levels of messengerRNA for MHC-α, MHC-β, KDR, TRT, Osteopontin, BMPr-II, Collagen II,Map-2, V-Mlc, and cTnT. In one aspect of the invention, the populationof DPMSCs co-express mRNA of each of the following: Oct-4 Isoforms A andB, Nanog, Sox-2, SSEA-4, c-Myc, Klf-4, and Rex-1.

Yet another way to characterize the population of DPMSCs of theinvention is by protein expression. One way that the protein expressioncan be determined is by immunofluorescence of the DPMSCs duringproliferation phase. Non-limiting examples of protein expression whichcan be detected in the DPMSC population of the invention include:Aggrecan, collagen I, FGFr-I, FGFr-II, c-TnT, collagen II, SMA,Neurofilament light, G-Fap, NSE, VWF, Cbfa-I, Gata-4, Msx-2, Neuro D,Nanog, Oct-4, SSEA-4. Immunoblot can also be used to determine proteinexpression of the DPMSCs during proliferation phase. Non-limitingexamples of protein expression which can be detected in the DPMSCpopulation of the invention include: ASA, Serca, β³-Tubulin,Synaptophysin, Msx-2, Oct-4, Connexin-43, Dlx-5, Neuro-D, Ca-Channel,and Cbfa-I.

DPMSCs express mRNA for POU-domain transcription factor Oct-4, which isrequired to maintain undifferentiated state of embryonic stem (ES)cell/embryonal carcinoma (EC) cell. Oct-4 is a transcription factorexpressed in the pregastrulation embryo, early cleavage stage embryo,cells of the inner cell mass of the blastocyst, and in embryoniccarcinoma (EC) cells (Nichols J, et al Cell 95:379-91, 1998), and isdown-regulated when cells are induced to differentiate. Expression ofOct-4 plays an important role in determining early steps inembryogenesis and differentiation. Oct-4, in combination with Rox-1,causes transcriptional activation of the Zn-finger protein Rex-1, alsorequired for maintaining ES undiffereniated (Rosfjord E, Rizzino A.,Biochem Biophys Res Commun 203:1795 802, 1997; Ben-Shushan E, et al, MolCell Biol 18:1866-78, 1998). In addition, Sox-2, expressed in ES/EC, butalso in other more differentiated cells, is needed together with Oct-4to retain the undifferentiated state of ES/EC (Uwanogho D., et al., MechDev 49:23-36, 1995).

Human DPMSCs of the invention express and stain positive with SSEA-4.Oct-4 protein levels tend to decrease in human DPMSCs cultures beyond 40cell doublings, the results of which, without being bound by theory, maybe due to a partial loss of undifferentiated phenotype. Thus, thepresence of Oct-4, combined with SSEA-4, are markers that correlate withpresence of the most primitive cells in DPMSC cultures.

DPMSCs of the invention display different rates of proliferationdepending on how many doublings have occurred since the start of theculturing from the dental pulp source. Accordingly, in one aspect, theinvention encompasses an isolated population of DPMSCs that have anaverage doubling time of about 30-40 hours for the initial ten celldoublings. The average doubling time can be about 30, 31, 32, 33, 34,35, 36, 37, 38, 39 or 40 hours for the population of DPMSCs the initialten cell doublings. In one embodiment, the doubling time is about 36hours for the initial ten cell doublings. After the initial ten celldoublings, cell-doubling time can be about 28 hours until about 30-35cell doublings and then the rate slowly decreases thereafter. The DPMSCsof the invention encompass an isolated population of DPMSCs that have anaverage doubling time of 25-40 hours for the proliferation of the DPMSCsas averaged over the time in culture. In yet another aspect of theinvention, the average doubling time can be about 28 hours in 1.25-2.5%human serum medium and about 29 or 30 hours in 0.25-0.5% human serummedium. The estimated number of starting primary culture cells can beabout 80 to 800.

A population of DPMSCs of the invention can proliferate asundifferentiated, pluripotent DPMSCs for at least about a month,preferably about two months, even more preferably about three months ormore. Alternatively, the population of DPMSCs of the invention canproliferate as undifferentiated, pluripotent DPMSCs for at least about10 doublings, preferably at least about 20 doublings, and even morepreferably at least about 30, 40, 50, 60, or more doublings since thestart of the culture from the dental pulp source. The invention alsoencompasses a population of DPMSCs which have been grown fromcryopreserved DPMSCs.

In another aspect of the invention, the population of DPMSCs alsodisplay a reduction of telomere length as compared to internal controlsas a measure of telomere activity. As further detailed in the Examplesas one embodiment of the invention, the telomere length of DPMSCs fromtwo donors (age 6 years) cultured at reseeding densities of 2×10³cells/cm² was between 10-20 kbp. The telomere length of the internalcontrol 1301 cell line was estimated to be 100%. The mean telomerelength of DPMSCs was 18.4% P2 and 17.1% P5 (after thawed) compared withthe control. Accordingly, the DPMSCs of the invention encompass anisolated population of DPMSCs that have telomere length of less than 75%of the control cell line, preferably less than about 65%, preferablyless than about 55%, and more preferably less than about 45%.

The population of DPSMCs of the invention have the capability todifferentiate into one or more (such as two or all three) of the celltypes of ectodermal, endodermal, or mesodermal lineages. In anotheraspect, the population of DPMSCs of the invention have the capability todifferentiate into any one or more of the following: osteoblast,skeletal muscle cell, smooth muscle cell, cardiac muscle cell, glialcell, neuronal cell and hepatic cell. In another aspect, the populationof DPSMCs of the invention have the capability to differentiate into anyone or more of the following: a bone cell, skeletal muscle cell, smoothmuscle cell, cardiac muscle cell, glial cell, neuronal cell, skinepithelial cell, liver epithelial cell, pancreas epithelial cell,pancreas endocrine cell, pancreatic islet cell, pancreas exocrine cell,gut epithelium cell, kidney epithelium cell, epidermal associatedstructure, hair follicles, soft tissues surrounding teeth, dentin(teeth), enamel (teeth), and cement (teeth). The invention contemplatesany and all of the above parameters, as described in the above sectionsand elsewhere herein, in any combination, to describe and characterizethe DPMSCs.

IV. METHOD OF ISOLATING AND/OR CULTURING DENTAL PULP MARROW SIMILARCELLS

Dental pulp marrow similar cells (DPMSCs) isolated as described hereinmay be cultured using methods of the invention starting from a source ofdental pulp as described above. The dental pulp can be eitherenzymatically disaggregated or non-enzymatically disaggregated (e.g.,mechanical disaggregation). In one aspect, the desegregated mixedpopulation of cells are not subjected to any type of depletiontechniques (e.g., immunodepletion or physical or chemical depletion). Inanother aspect, the methods do not involve depleting cells (e.g.,mononuclear cells) expressing the following markers: CD3, CD14, CD19,CD38, CD66b and CD45⁺ glycophorin A.

The cells can then be plated in, from example, one or more of any typeof culturing vessel, such as a plastic culture dish, and maintained in aproliferation medium that is supplemented with various growth factors.The growth factors may be chosen from platelet-derived growth factor(e.g., PDGF-BB), epidermal growth factor (EGF), fibroblast growthfactor-b (FGF-b), insulin-like growth factor (IGF), insulin,dexamethasone, linoleic acid, ascorbic acid, and selenium to obtain apopulation of DPMSCs. In one embodiment, the medium may be supplementedwith all of these components. In one embodiment, the proliferationmedium is described in the Examples and is referred to here in Mid-freemedium. The growth factors which can be used include, but are notlimited to, 1-50 ng/ml (preferably about 5-15 ng/ml) platelet-derivedgrowth factor-BB (PDGF-BB), 1-50 ng/ml (preferably about 5-15 ng/ml)epidermal growth factor (EGF), 1-50 ng/ml (preferably about 5-15 ng/ml)insulin-like growth factor (IGF), 50 ng/ml (preferably about 5-15 ng/ml)fibroblast growth factor-b (FGF-b), with 10⁻¹⁰ to 10⁻⁸ M dexamethasoneor other appropriate steroid, 0-1 μg/L linoleic acid, and 10-50 mg/Lascorbic acid.

In another aspect of the invention, the DPMSCs of the invention arecultured in media that comprises insulin at a concentration of about 10to about 50 μg/ml, transferrin at a concentration of greater than 0 butless than about 10 μg/ml, selenium at a concentration of about 0.1 toabout 5 μg/ml, linoleic acid at a concentration of about 0 to about 1μg/m, dexamethasone at a concentration of about 0.005 to 0.15 μM,L-ascorbic acid at a concentration of about 10-50 mg/L, platelet-derivedgrowth factor at a concentration of about 5 to about 15 ng/ml, epidermalgrowth factor at a concentration of about 1 to 15 ng/ml, insulin-likegrowth factor at a concentration of 1 to about 15 ng/ml, and ml andfibroblast growth factor-b 1 to at a concentration of about 15 ng/ml.

In another aspect of the invention, the DPMSCs of the invention arecultured in media that comprised of a proliferation medium containingF-12 Coon's modified/Ambesi's modified/Medium 199/CMRL 1066 supplementedwith about 1.25% of Human serum, platelet-derived growth factor-BB at aconcentration of about 1 to about 50 ng/ml, epidermal growth factor at aconcentration of about 1 to about 50 ng/ml, insulin-like growth factor-Iat a concentration of about 1 to about 50 ng/ml, fibroblast growthfactor-I at a concentration of about 1 to about 50 ng/ml, dexamethasoneat a concentration of about 10⁻¹⁰ to about 10⁻⁸ M, linoleic acid at aconcentration of about 20 to about 100 μg/L, ascorbic acid at aconcentration of about 10 to about 50 mg/L and gentamycin at aconcentration of about 0.5 ml/L. In another aspect of the invention,DPMSCs are placed, optionally dissociated, in a medium containingCollagenase II at a concentration at about 1000 U/mL and a CTC solution.The CTC solution contains Trypsin at a percentage by volume of about0.5%, Collagenase II at a concentration of about 22 U/mL and chickenserum at a percentage by volume of about 0.2%. In yet another aspect ofthe invention, dental pulp population of cells is not subjected to anytype of depletion techniques (e.g., immunodepletion or physical orchemical depletion) and when colonies develope in primary culturereaches confluence, cells can be detached by the CTC solution andsub-cultured in the proliferation medium. The culture is maintainedsemi-confluently to prevent cell differentiation.

In one alternative, the DPMSCs can be placed in a cell culture containerwith an extracellular matrix (ECM) substrate. In another alternative,the DPMSCs can be placed in a cell culture container without anextracellular matrix (ECM) substrate. In yet another alternative, theDMPSCs can be placed in a cell culture container such that it settlesand forms a three-dimensional structure. As is known to one of skill inthe art, three-dimensional structures, such as scaffolding (includingbioscaffolding), can be used to culture the DPMSCs and/or differentiatethe DPMSCs to cells and/or tissues. For example, the DPMSCs can becultured with scaffolding to grow trachea, blood cells, brain tissue,kidney, pancreas, liver, heart, lung, spinal cord, nerve(s), neuralcells, neurons, cartilage, bone, and other cells and/or tissues thatcould be used in regenerative medicine.

Culture in low-serum medium is preferred to maintain the cells in theundifferentiated state. Serum can be human serum or non-human serum,depending on the species of DPMSCs being isolated. Human serum can beautologous. Low serum as used herein refers to a level by percentage byvolume of about 0.5-2.5%. In one aspect, the present invention providesfor methods for isolating DPMSCs and subsequent proliferation thereofthat involve adding a low 1.25% human serum medium containing insulin,selenium, linoleic acid, dexamethasone, and platelet derived growthfactor. The low-human serum medium may be F12 in admixture with M-199and CMRL-1066. The insulin may be optionally present at a concentrationof from about 1 to about 5 μg/ml. Low serum medium may contain aneffective amount of transferrin at a concentration of greater than 0 butless than about 10 μg/ml, the selenium may be present at a concentrationof about 0.1 to about 5 μg/L, the linoleic acid may be present at aconcentration of 0 to about 1 μg/mL, and the dexamethasone may bepresent at a concentration of about 10⁻¹⁰ to 10⁻⁸ M. The low-serummedium may contain about 10-50 mg/L-ascorbic acid. The low-serum mediummay contain about 5 to about 15 ng/ml platelet-derived growth factor, 1to about 15 ng/ml epidermal growth factor, 1 to about 15 ng/mlinsulin-like growth factor, and 1 to about 15 ng/ml fibroblast growthfactor-b. The invention also contemplates the use of serum-free mediawith the addition of any one or all of the growth factors componentslisted above.

One of skill in the stem cell art can routinely culture the DPMSCs ofthe invention by using the media conditions described herein forproliferation. Once established in culture, cells can be frozen andstored as frozen stocks. In one embodiment, the cells are frozen andstored using the proliferation medium described herein with 10% DMSO.Other methods for preparing frozen stocks for cultured cells are alsoknown to those of skill in the art. In addition to culturing DPMSCs forproliferation, the population of DPMSCs can also be cultured in mediawith other factors added to induce differentiation into progeny cells.

The invention also includes DPMSC populations produced by the culturingmethod(s) described herein. The invention also includes cells culturedunder conditions described herein, including cells initially cultured(for example, upon introduction into culture media) and along any pointof the culture process.

In another aspect of the invention, a population of dental pulp cellswith broad differentiation potential, as well as mesodermal-,endodermal-, and ectodermal-derived lineages can be isolated via theunique expansion/selection procedure presented in the invention, whichinvolves the use of low percentages of autologous human serum.

III. INDUCING DPMSCS TO DIFFERENTIATE TO FORM COMMITTED PROGENITORS ANDTISSUE-SPECIFIC CELL TYPES AND USES THEREOF

The present invention further provides for differentiated cells derivedfrom the pluripotent DPMSCs described herein as well as methods toinduce differentiation of these cells. In one aspect, the inventionencompasses DPMSCs which can differentiate into any one or more of thefollowing: splanchnic mesoderm cells, muscle cells, neuronal cells,cardiomyocytes and hepatocytes. In another aspect, the inventionencompasses DPMSCs which can differentiate into any one or more of thefollowing: a bone cell, skeletal muscle cell, smooth muscle cell,cardiac muscle cell, glial cell, skin epithelial cell, liver epithelialcell, pancreas epithelial cell, pancreas endocrine cell or islet cell,pancreas exocrine cell, gut epithelium cell, kidney epithelium cell, oran epidermal associated structure (e.g., hair follicle). In anotheraspect, the invention encompasses DPMSCs which can differentiate intoprogeny cells that can form soft tissues surrounding teeth or may formteeth (e.g., dentin, enamel and cement). In yet another aspect, theinvention encompasses DPMSCs which can differentiate into any one ormore of the following: osteoblast cells and myocytes.

The present invention also provides for isolated pluripotent DPMSCs asdescribed herein, wherein genome of the cell has not been altered byinsertion of pre-selected isolated DNA, by substitution of a segment ofthe cellular genome with preselected isolated DNA, or by deletion of orinactivation of at least a portion of the cellular genome.

Using appropriate growth factors, chemokines, and cytokines as describedherein and/or also known to one of skill in the art, DPMSCs of thepresent invention can be induced to differentiate to form a number ofcell lineages, including, for example, a variety of cells of mesodermalorigin as well as cells from neuroectodermal origin (e.g., glial cells,oligodendrocytes, and neurons) as well as endodermal origin (e.g.,hepatocytes). The invention encompasses these methods.

A. Splanchnic Mesoderm

Splanchnic mesoderm may be grown by using the homogeneous population ofDPMSCs of the invention. In one embodiment, to grow osteoblasts, 20,000cells/cm² of DPMSCs can be cultured with about 10⁻⁶ to 10⁻⁸ M(preferably about 100 nM) dexamethasone, β-glycerophosphate and 0.5-3 mM(preferably 1 mM) ascorbic acid. To demonstrate presence of osteoblasts,Von Kossa staining (silver reduction of CaPo4) can be used, orantibodies against osteonectin, osteopontin and osteocalcin(immunohistochemistry/Western/rt-PCR), after about 3 months of culture.X-Ray diffraction patterns and infrared spectra can also be used toevaluate the presence of Hydroxyapatite formation.

B. Muscle

DPMSCs can be induced to undergo differentiation to any muscle phenotypeby plating confluent DPMSCs prior to induction of differentiation. Inone aspect, to induce muscle cell differentiation, about 10,000cells/cm² DPMSCs cells can be treated with DMEM 5% FBS with IBMX 0.1-1mM (preferably 0.5 mM) and VEGF 5-20 ng/mL (preferably 10 ng/mL).Differentiation can be evaluated by using Western blot andimmunofluorecence. Skeletal muscle differentiation in vitro can bedemonstrated by detecting sequential activation of myogenin, actinin,skeletal actin and skeletal myosin, either by immunohistochemistry orWestern blot analysis using standard techniques known to those of skillin the art and commercially available antibodies. Skeletal actin, Serca2a, Ca-channel and Msx-2 can be detected as early as 15 days afterinduction, and skeletal myosin at 40 days. By immunohistochemistry,about 70-80% of cells can express mature muscle proteins after 14 days.Treatment with differentiation medium can result in the expression ofASA, Ca-channel, SMA, c-TnT, Connexin-43, Gata-4, Myosin heavy chain,Myogenin, Nkx-2.5, N-caderin, Serca-2a ATPase during the 15 days ofculture. In addition, skeletal myosin can be organized and co-expressedwith ASA at 40 days, like actinin. Smooth muscle actin can be detectedat two days after induction and can persist. Ryanodine receptor may notbe expressed.

C. Neuronal Cells

DPMSCs can be induced to undergo differentiation to neuronal cells. Asfurther detailed in the Examples for one embodiment, neural developmentcan be induced by culturing DPMSCs in neural differentiation medium.Neural differentiation medium can include a minimum essential medium,such as DMEM-HG. Neural differentiation medium typically contains one ormore additional additives, such as antibiotics, growth factors,nutrients, or combinations thereof. Specific non-limiting examples ofsuch additives include NT-3 (from about 1 ng/ml to about 100 ng/ml), NGF(from about 1 ng/ml to about 100 ng/ml), BDNF (from about 5 ng/ml toabout 500 ng/ml), insulin (from about 0.1 μg/ml to about 10 μg/ml), IBMX(from about 0.1 μM to about 100 μM) and indomethacin (from about 10 μMto about 500 μM). In another aspect, this medium can include any one ormore of the following: DMEM-HG, 1×ITS, and FGF (e.g., at about 0.5-100ng/mL, preferably about 10 ng/mL). The medium may also contain one ormore of the following cytokines in order to induce differentiation intocertain cell types: 5-50 ng/mL BDNF (preferably about 16 ng/mL) forobtaining dopaminergic neurons. The choice of growth factors to inducedifferentiation of DPMSCs into neural cells can be based on what isknown in embryonic development of the nervous system or from studiesthat evaluated in vitro CNS differentiation.

In one aspect of the invention, neural specification is induced byincubating DPMSC cells at about 3,000 cells/cm² in DMEM-high glucosewith 10% FBS. Medium is replaced after 24 hours with a neural commitmentmedium containing DMEM-high glucose, 10% FBS with B27, EGF at aconcentration of about 10 ng/ml and bFGF at a concentration of about 20ng/ml for 15 days. Cells are passed 1:3 and placed in the neuralcommitment medium with NT-3 at a concentration of about 20 ng/ml, NGF ata concentration of about 20 ng/ml, BDNF at a concentration of about 50ng/ml, BHA at a concentration of about 20 μM, IBMX at a concentration ofabout 50 μM, ATRA at a concentration of about 1 μM, and Progesteron at aconcentration of about 20 nM.

In another aspect of the invention, neural differentiation is induced bycontacting neurally committed cells with a neural differentiation mediumthat consists of DMEM, NT-3 at a concentration of about 20 ng/ml, NGF ata concentration of about 20 ng/ml, BDNF at a concentration of about 50ng/ml, insulin at a concentration of about 5 μg/ml, indomethacin at aconcentration of about 2000/1, and IBMX at a concentration of about 0.5mM. Neurally committed DPMSC cells are incubated in the neuraldifferentiation medium for about 1 day.

In one aspect of the invention, DPMSC cells can be allowed to settle tothe bottom of the culture dish to form a 3D structure. Neuraldifferentiation may be expected to occur, for example, in a 100%humidified atmosphere of 95% air, 5% CO2 at 37°. Neural differentiationmay be detected in about 4 weeks. In another aspect of the invention,the morphology of the neural-induced DPMSC cells closely resembled thatof mature neurons: they had a large number of neurites, increased fromabout 3 to about 4 weeks after differentiation, and with significantbranching.

After about 2-4 weeks, the culture of cells can be examined to determinethe growth of astrocytes and neurons. Astrocytes can be identified asglial-fibrilar-acidic-protein (GFAP) positive cells, oligodendrocytescan be identified as glucocerebroside positive (GalC) and neurons can beidentified as cells that express in a sequential fashion NeuroD,Tubulin-IIIB (Tuji), synaptophysin and neurofilament-68, 160-200 kDa.

In one non-limiting example, the number of neurites per neuron canincrease from 3±1, to 5±1 and 7±2 from 2, 3 to 4 weeks afterdifferentiation. Differentiation to cells with characteristics ofneurons can be confirmed by demonstrating presence of GFAP,neurofilament-160, synaptophysin, β³-Tubulin by Western blot. The use ofimmunofluorescence can reveal the presence of synaptophysin, Synapsyn I,Neurofilament 160, β³-Tubulin, N-caderin, Tyrosine hydroxylase, Neuro-D,N-Cadherin, Neurofilament-68, and NSE.

The use of rt-PCR can show that cells express β³-Tubulin,Neurofilament-68, -160, -200 kDa, vimentin, NSE, β³-Tubulin, G-Fap,Glypican, Musashi, n-Nos, but not MAP-2. Other growth factors that arespecifically expressed in the brain and that can affect neuraldevelopment in vivo and in vitro include brain derived neurotrophicfactor (BDNF), glial derived neurotrophic factor (GDNF) and ciliaryneurotrophic factor (CNTF). BDNF is a member of the nerve growth factorfamily that promotes in vitro differentiation of NSC, human subependymalcells, and neuronal precursors to neurons and promotes neurite outgrowthof hippocamal stem cells in vivo. In one non-limiting example, DPMSCstreated with 5-20 ng/mL (preferably 16 ng/mL) BDNF and EGF coulddifferentiate into tyrosine hydroxylase positive neurons, consistentwith the known function of BDNF to support survival of dopaminergicneurons of the substantia nigra.

In one aspect of the invention, neural stem precursor marker, Vimentin,is expressed both in proliferation and neural differentiation, butduring the induction, it is less organized. Neuro-endocrine nuclearfactor, Neuro-D/Beta-2, is expressed only during proliferation.Expression of Nestin, another neurofilament neural stem marker, isdecreased from proliferation to the induction stage. β³-Tubulin isexpressed in about 99% of DPMSC cells after differentiation. Structuralneurofilaments NF-160 and NF-200 are expressed only duringdifferentiation, the positivity of expression is about 50% for NF-160and to a lesser extent for NF-200, which is consistent with a matureneural phenotype. In contrast, NF-68 protein is expressed duringproliferation and after neural induction, as shown for NSE.

In another aspect of the invention, synaptic vesicle trafficking markersSynapsyn-I and synaptophysin are expressed after differentiation in allneural induced DPMSC cells, at the same time, Tyrosine hydroxylase,N-caderin, and p75-NGFr are detected only after induction. TheOligodendrocyte marker-4 is not expressed. G-Fap, astrocyte marker, isexpressed during both proliferation and neural differentiation, but isless organized during induction. GFAP and beta3-tubulin areco-expressed.

D. Cardiomyocytes

Differentiation to cardiomyocytes can be achieved by plating confluentDPMSC prior to induction of differentiation. In one aspect, to inducecardiomyocyte cell differentiation, confluent (e.g., 10,000 cells/cm²)DPMSC cells can be treated with DMEM HG with FBS (from about 1% to about10%), IBMX (from about 0.1 mM to about 10 mM), and VEGF (from about 1ng/ml to about 20 ng/ml) and cultured at condition favorable to thedifferentiation, for example, in a 100% humidified atmosphere of 95%air, 5% CO₂ at 37°. Cardiomyocyte differentiation may be detectedbetween about 2 weeks to about 3 months. Muscle differentiation in vitrocan be demonstrated by detecting sequential activation of actinin,skeletal and cardiac actin and skeletal myosin, either byimmunohistochemistry or Western blot and rt-PCR analysis usingcommercially available antibodies and specific primers. Expression ofASA, Ca-channel DHPR, SMA, c-TnT, Connexin-43, Msx-2, Myosin heavychain, Gata-4, Serca 2A can also be determined as an indication ofdifferentiation down the cardiomyocyte pathway.

In another aspect of the invention, differentiation to any musclephenotype can be achieved by plating DPMSC at 11,000 cells/cm² prior toinduction of differentiation. To induce cardiomyocyte celldifferentiation, confluent DPMSC cells can be treated with DMEM withabout 5% FCS, bFGF at a concentration of about 10 ng/mL, VEGF at aconcentration of about 10 ng/mL, and IGF-1 at a concentration of about10 ng/mL. Cells can be cultured to reach confluency for about 2 weeks toabout 3 months with medium exchanges every 4 days.

Cardiomyocyte differentiation may be expected to occur, for example, ina 100% humidified atmosphere of 95% air, 5% CO2 at 37°. In one aspect ofthe invention, cardiomyocyte differentiation may be detected betweenabout 2 weeks to about 3 months. During this differentiation period,cells became long and irregular. Co-expression of Atrial natriureticpeptide (ANP), Smooth muscle actin (SMA), Skeletal muscle actin (SKMA),Cardiac actin (CA), cardiac-Troponin T (c-TNT), Miocyte enancerfactor-2a (MEF-2a), and Myosin heavy chain (Mhc) can be detected duringproliferation and differentiation.

In another aspect of the invention, mRNA expression level of Gata-4 andNkx-2.5 is low in both proliferation and differentiation phases, whereasMsx-2 m-RNA expression is high. Expression of Myocardin decreases afterdifferentiation. In yet another aspect of the invention, cells canorganize filaments of α-actinin, α-sarcomeric actin and Myosin heavychain. α-sarcomeric actin and Myosin heavy chain can be co-expressed andorganized in a fraction of differentiating cells.

In one aspect of the invention, gap junctions can be demonstrated by thepresence of connexin-43 in proximity to cell to-cell contact sites.L-Type calcium channels, Serca-2 ATPase pump, c-TNT can also beidentified in differentiated cells. SMA can be expressed at high levelduring the proliferation stage and the expression decreases afterinduction without losing the filamentous structure. Expression of Msx-2decreases constantly from proliferation to differentiation stage,whereas GATA-4 expression is lost after cardiomyocyte induction.

E. Hepatic Cells

In one aspect, differentiation to hepatic cells can be achieved byplating confluent (e.g., 20,000 cells/cm²) DPMSC prior to induction ofdifferentiation with DMEM low glucose 1-10% FCS, hepatocyte growthfactor (HGF) (from about 1 ng/ml to about 100 ng/ml), oncostatin (OSM)(from about 1 ng/ml to about 100 ng/ml), nicotinamide (from about 1 mMto about 100 mM), LDL (from about 0.1 μg/ml to about 10 ng/ml), FGF-4(from about 1 ng/ml to about 100 ng/ml), insulin (from about 1 μg/ml toabout 10 μg/ml), linoleic acid (from about 180 μg/L to about 1 mg/L),and glucose (from about 1 g/L to about 10 g/L) and cultured underconditions favorable to the differentiation. One of skill in the art canascertain the differentiation pathway to hepatic cells by observingsmall epithelioid cells that express and secrete albumin. In addition,the cells can be tested for expression of mRNA for HGF receptor,cytokeratin 19, Abcg-2, MDR-I, transferrin, somatostatin,erythropoietin, and cytochrome P-450 subunit 2e1. In addition, thepresence and secretion of albumin, urea, cytokeratin-8-18-19, HNF-3β andHNF-4-α may also indicate possible differentiation to hepatic cells.

In another aspect of the invention, hepatocyte differentiation can beachieved by incubating confluent DPMSCs with DMEM low glucose 1% FCS,hepatocyte growth factor at a concentration of about 20 ng/mL,Oncostatin at a concentration of about 10 ng/ml, Nicotinammide at aconcentration of about 10 mM, LDL at a concentration of about 1.25μg/mL, FGF-4 at a concentration of about 10 ng/mL, Insulin (from about 1μg/ml to about 10 μg/ml), Linoleic acid at a concentration of about0.00018 g/L and glucose at a concentration of about 1.25 g/L for about14 to about 37 days. Hepatic differentiation may be expected to occur,for example, in a 100% humidified atmosphere of 95% air, 5% CO2 at 37°,and hepatic differentiation may be detected after about 5 weeks.

In another aspect of the invention, after about 14 to about 37 days,differentiated cells can assume a globular shape with an eccentricnucleus. During proliferation to differentiation stage, these cells canshow increased expression of Albumin, Transferrin, Somatostatin,Erytropoietin and Cytochrome P-450 subunit 2e1, constant expression ofc-MET/HGF-r, Abcg-2, MDR-I, and decreased expression of cytokeratin-19.In yet another aspect of the invention, a large percentage of cells canbe stained positive for the hepatic epitelial specific cytokeratins 8,18 and 19 after differentiation with a small filamentous organization.Cells can express both hepatocyte nuclear factor 4α and 3β, afterhepatic induction. In another aspect, cells can acquire severalhepatocytic functions such as the ability to store glycogen asdemonstrated by PAS staining and to produce albumin and urea as examinedby testing the concentration and dosage of these factors in culturesupernatants.

IV. KITS CONTAINING DPMSCS OR DPMSC ISOLATION AND CULTURE COMPONENTS

DPMSCs of the present invention (and/or differentiated cells derivedfrom DPMSCs of the invention) can be provided in kits, with appropriatepackaging material. For example, DPMSCs can be provided as frozen stocks(in appropriate preservation media, for example, as described herein),accompanied by separately packaged appropriate factors and media, aspreviously described herein, for culture in the undifferentiated state.Additionally, separately packaged factors for induction ofdifferentiation, as previously described, can also be provided.

Kits containing effective amounts of appropriate factors for isolationand culture of stem cells (such as those from a patient) are alsoprovided by the present invention. Upon obtaining a dental pulp from anindividual (such as a patient), the technician selects the stem cellsusing the method(s) described herein or using one or more selectiontools based on the marker profile of the DPMSCs described herein (e.g.,anti-CD45 and anti-glycophorin A) provided in the kit, then cultures thecells as described by the method(s) of the present invention, usingculture medium supplied as a kit component. The composition of the basicculture medium has been previously described herein. The kits may alsocontain instructions addressing any one or more methods of culturing,differentiating, or using the cells as described herein.

V. METHODS OF USING DPMSCS AND DIFFERENTIATED CELLS DERIVED FROM DPMSCS

DPMSCs of the invention have many uses, both in its undifferentiatedstate as well as in its differentiated state. The invention provides formethods of administering DPMSCs to an individual in need of suchtreatment. Accordingly, in some aspects of the invention, DPMSCs can beadminstered the individual for therapeutic assistance. In all of theconditions listed below, it is to be understood that the DPMSCs anddifferentiated cells derived from the DPMSCs can not only be used fortreatment purposes but also to assist in the therapy for the conditions.One of skill in the art may readily determine the appropriate state(differentiated vs. undifferentiated) that a population of DPMSCs shouldbe in when the population is being used, for example, for therapeuticpurposes to treat a condition (e.g., tissue repair and/or assisting oraiding treatment). In some circumstance, the DPMSCs is used in itsundifferentiated, pluripotent state. The DPMSCs may be optionallymanipulated (e.g., genetically) to provide added benefits to theindividual. In other instances, it may be appropriate to culture theDPMSCs in a manner to induce differentiation down a particular pathwaywhere the individual in need of could benefit from such cells.

DPMSCs, and the medium used for DPMSC selection of the presentinvention, hold strong promise in clinical reparative medicine for thetreatment of degenerative or inherited diseases and are free of theethical concerns raised by the use of ES cells. Autologous ex vivoexpanded DPMSC cells could be used for autologous implantation aimed torepair damaged, aged or diseased tissues and organs. The ability tostably transduce DPMSC cells with specific genes, can also enable thegenetic manipulation of autologous cells for the treatment ofdegenerative and congenital disorders.

DPMSCs of the present invention that have been induced to differentiateto form bone cells can be used as cell therapy and/or assist celltherapy for tissue regeneration in osteoporosis, Paget's disease, bonefracture, osteomyelitis, osteonecrosis, achondroplasia, osteogenesisimperfecta, hereditary multiple exostosis, multiple epiphysealdysplasia, Marfan's syndrome, mucopolysaccharidosis, neurofibromatosisor scoliosis, reconstructive surgery for localized malformations, spinabifida, hemivertebrae or fused vertebrae, limb anomalies, reconstructionof tumor-damaged tissue, and reconstruction after infection, such asmiddle ear infection.

DPMSCs can be induced to differentiate to form skeletal muscle cells forcell therapy and/or assist cell therapy for tissue repair in thetreatment of Duchene muscular dystrophy, Becker muscular dystrophy,myotonic dystrophy, skeletal myopathy, and reconstructive surgery torepair skeletal muscle damage. DPMSCs can be induced to differentiate toform smooth muscle cells for cell therapy or tissue repair in thetreatment of developmental abnormalities of the gastrointestinal system,such as oesophageal atresia, intestinal atresia, and intussusception, aswell as for replacement of tissues after surgery for bowel infarction orcolocolostomy. Smooth muscle cells formed from the DPMSCs of the presentinvention can also be used for bladder or uterine reconstruction, forneovascularization, for repair of vessels damaged by, for example,atherosclerosis or aneurysm. Smooth muscle precursor cells (mesangialcells) can be used as an in vitro model for glomerular diseases or forcell therapy or tissue regeneration in diabetic neuropathy. Smoothmuscle precursors can also be used to repair macula densa of the distalconvoluted tubule or juxtaglomerular tissues, which play a role in bloodpressure regulation.

Cardiomyocytes derived from the DPMSCs can be useful for cell therapyand/or assist cell therapy for tissue repair for treating heart tissuedamaged following myocardial infarction, in conjunction with congestiveheart failure, during valve replacement, by congenital heart anomalies,or resulting from cardiomyopathies or endocarditis. Cells can bedelivered locally, especially by injection, for increased effectiveness.

Microglial cells differentiated from DPMSCs can be used to treat spinalcord injuries and neurodegenerative disorders, such as Huntingtonsdisease, Parkinsons disease, Multiple Sclerosis, and Alzheimers disease,as well as repair of tissues damaged during infectious disease affectingthe central nervous system. Microglial cells that have been geneticallyaltered to produce cytokines can also be used for transplantation forthe treatment of infectious disease in the central nervous system whereaccess is limited due to the blood-brain bather. Glial cells can also beused to produce growth factors or growth factor inhibitors forregeneration of nerve tissue after stroke, as a consequence of multiplesclerosis, amylotropic lateral sclerosis, and brain cancer, as well asfor regeneration after spinal cord injury.

Microglial cells differentiated from DPMSCs can be induced todifferentiate into neuroectodermal cells and used to treat spinal cordinjuries and neurodegenerative disorders, such as Huntingtons disease,Parkinsons disease, Multiple Sclerosis, and Alzheimers disease, as wellas repair of tissues damaged during infectious disease affecting thecentral nervous system. Microglial cells that have been geneticallyaltered to produce cytokines can also be used for transplantation forthe treatment of infectious disease in the central nervous system whereaccess is limited due to the blood-brain barrier. Glial cells can alsobe used to produce growth factors or growth factor inhibitors forregeneration of nerve tissue after stroke, as a consequence of multiplesclerosis, amylotropic lateral sclerosis, and brain cancer, as well asfor regeneration after spinal cord injury. DPMSCs induced to formoligodendrocytes and astrocytes, for example, can be used for transplantinto demyelinated tissues, especially spinal cord, where they functionto myelinate the surrounding nervous tissues. This technique has beendemonstrated effective in mice, using embryonic stem cells as the sourceof oligodendrocyte and astrocyte precursors (Brustle, O., et al.,Science (1999) 285: 754-756). The DPMSCs of the present invention canexhibit the broad range of differentiation characteristic of embryoniccells, but provide the added advantage of contributing autologous cellsfor transplant. Accordingly, the DPMSCs of the invention or itsneuronally related differentiated cell can be used to treat a diseasewith neural deficits or degeneration including among but not limited tostroke, Alzheimer's, Parkinson's disease, Huntington's disease,AIDS-associated dementia, spinal cord injury, and metabolic diseaseseffecting the brain or other nerves.

Other uses for the cells of the invention include providing therapeuticenzymes, proteins, or other biological products by performing an inutero transplantation of a population of the DPMSCs to form chimerism ofcells or tissues to produce human cells in prenatal or post-natal humansor animals following transplantation, wherein the cells producetherapeutic enzymes, proteins, or other biological products in the humanor animal so that genetic defects are corrected.

The present invention includes methods of providing therapy for damagedtissue in a human individual in need thereof comprising: (a) culturingthe DMPSCs to proliferate them; and (b) contacting an effective amountof the expanded DPMSCs with the damaged tissue of said individual to aidtherapy. The cells may be introduced into the body of the individual bylocalized injection, or by systemic injection. The cells may beintroduced into the body of the individual in conjunction with asuitable matrix implant. The matrix implant may provide additionalgenetic material, cytokines, growth factors, or other factors to promotegrowth and differentiation of the cells. The cells may be encapsulatedprior to introduction into the body of the individual, such as within apolymer capsule.

The present invention also provides methods of using DPMSCs to identifygenetic polymorphisms associated with physiologic abnormalities,involving isolating the DPMSCs from a statistically significantpopulation of individuals from whom phenotypic data can be obtained,expanding the DPMSCs from the statistically significant population ofindividuals to establish DPMSC cultures, identifying at least onegenetic polymorphism in the cultured DPMSCs, inducing the culturedDPMSCs to differentiate, and characterizing aberrant metabolic processesassociated with said at least one genetic polymorphism by comparing thedifferentiation pattern exhibited by DPMSCs having a normal genotypewith the differentiation pattern exhibited by DPMSCs having anidentified genetic polymorphism.

The present invention further provides methods for treating cancer (orin some embodiments, methods of delivering a therapeutic protein to anindividual with cancer), in an individual by genetically altering DPMSCsto express a tumoricidal protein, an anti-angiogenic protein, or aprotein that is expressed on the surface of a tumor cell in conjunctionwith a protein associated with stimulation of an immune response toantigen, and introducing an amount of the genetically altered DPMSCsinto the individual effective to generate an anti-cancer effect (e.g.,modify cultured cells and use them in different ways to halt growth ofor kill cancer cells).

The present invention provides methods of using DPMSCs to characterizecellular responses to biologic or pharmacologic agents by isolatingDPMSCs from a statistically significant population of individuals,expanding the DPMSCs from the statistically significant population ofindividuals to establish a plurality of DPMSC cultures, contacting theDPMSC cultures with one or more biologic or pharmacologic agents,identifying one or more cellular responses to the one or more biologicor pharmacologic agents, and comparing the one or more cellularresponses of the DPMSC cultures from individuals in the statisticallysignificant population.

In another aspect, the DPMSCs cells of the invention can be used toproduce tooth component material for treatment of dental disease. Inanother aspect, the DPMSCs cells of the invention can be used to developskin epithelial tissue derived from pluripotent stem cells that can beutilized for skin grafting and plastic surgery. In another aspect, theDPMSCs cells of the invention can be used to enhance muscle, such as inthe penis or heart. In another aspect, the DPMSCs cells of the inventioncan be used to produce blood ex vivo for therapeutic use, or to producehuman hematopoietic cells and/or blood in prenatal or post natal animalsfor human use. In another aspect, the DPMSCs cells of the invention canbe used as a therapeutic to aid in the recovery of a patient fromchemotherapy or radiation therapy in treatment of cancer, in thetreatment of autoimmune disease, to induce tolerance in the recipient.In another aspect, the DPMSCs cells of the invention can be used totreat AIDS or other infectious diseases.

In another aspect, the DPMSCs cells of the invention can be used totreat cardiac diseases including, but not limited to, myocarditis,cardiomyopathy, heart failure, damage caused by heart attacks,hypertension, atherosclerosis, and heart valve dysfunction. Agenetically engineered pluripotent mammalian derived stem cell, or itsdifferentiated progeny, can be used to treat a disease associated withCNS deficits or damage.

A population of DPMSCs or their differentiated progeny such as stromalcells can be used to support the growth and differentiation of othercell types in vivo or in vitro, including but not limited tohematopoietic cells, pancreatic islet or beta cells, hepatocytes, etc.The stem cell, or cartilage differentiated progeny, can be used to treata disease of the joints or cartilage including but not limited tocartilage tears, cartilage thinning, and osteoarthritis. Moreover, thestem cells or their osteoblast differentiated progeny can be used to aidamelioration of a process having deleterious effects on bone includingamong but not limited to bone fractures, non-healing fractures,osteoarthritis, “holes” in bones caused by tumors spreading to bone suchas prostate, breast, multiple myloma etc.

The present invention also encompasses methods of providing for adatabase of at least one gene profile of DPMSCs as described herein, andthe use of this databank to aid in drug discovery. Accordingly, in oneaspect, the invention provides for methods of providing a database ofgene profiles of a pluripotent derived stem cell to aid in drugdiscovery by: (a) determining the gene profile from DPSMCs from at leastone individual, wherein the gene profile involves at least one gene; and(b) storing the gene profile(s) on an accessible medium.

The cells of the present invention can be used in cell replacementtherapy and/or gene therapy to treat congenital neurodegenerativedisorders or storage disorders such as, for instance,mucopolysaccharidosis, leukodystrophies (globoid-cell leukodystrophy,Canavan disease), fucosidosis, GM2 gangliosidosis, Niemann-Pick,Sanfilippo syndrome, Wolman disease, and Tay Sacks. They can also beused for traumatic disorders such as stroke, CNS bleeding, and CNStrauma; for peripheral nervous system disorders such as spinal cordinjury or syringomyelia; for retinal disorders such as retinaldetachment, macular degeneration and other degenerative retinaldisorders, and diabetic retinopathy.

The present invention also provides methods of using specificallydifferentiated cells for therapy comprising administering thespecifically differentiated cells to an individual in need thereof. Itfurther provides for the use of genetically engineered pluripotent stemcells to selectively express an endogenous gene or a transgene, and forthe use of DPMSCs grown in vivo for transplantation/administration intoan individual to treat a disease. For example, neuroretinal cellsderived from pluripotent stem or DPMSCs can be used to treat blindnesscaused by, but not limited to, neuroretinal disease caused by, but notlimited to, macular degeneration, diabetic retinopathy, glaucoma, orretinitis pigmentosa. The cells can be used to engraft a cell into anindividual comprising administering autologous, allogenic or xenogeniccells, to restore or correct tissue specific metabolic, enzymatic,coagulation, structural or other function to the mammal. The cells canbe used to engraft a cell into an individual, causing thedifferentiation in vivo of cell types, and for administering thedifferentiated stem cells into the mammal. The cells, or their in vitroor in vivo differentiated progeny, can be used to correct a geneticdisease, degenerative disease, cardiovascular disease, metabolic storagedisease, neural, or cancer disease process.

Several approaches may be used for transplantation to prevent immunerejection. For universal donor cells: DPMSC can be manipulated to serveas universal donor cells for cell and gene therapy to remedy genetic orother diseases and to replace enzymes. Undifferentiated DPMSCs expressmRNA and very low protein percentages for HLA-type I, HLA-type II.DPMSCs can be modified to serve as universal donor cells by eliminatingHLA-type I and HLA-type II antigens, and potentially introducing theHLA-antigens from the prospective recipient to avoid that the cellsbecome easy targets for NK-mediated killing, or become susceptible tounlimited viral replication and/or malignant transformation. Eliminationof HLA-antigens can be accomplished by homologous recombination or viaintroduction of point-mutations in the promoter region or byintroduction of a pointmutation in the initial exon of the antigen tointroduce a stop-codon, such as with chimeroplasts. Transfer of the hostHLA-antigen can be achieved by retroviral, lentiviral, adeno-associatedvirus or other viral transduction or by transfection of the target cellswith the HLA-antigen cDNA's. DPMSCs can be used to establish and setamount or a given range or level of a protein in the body or blood.

For intrauterine transplant to circumvent immune recognition: DPMSCs canbe used in intrauterine transplantation setting to correct geneticabnormalities, or to introduce cells that will be tolerated by the hostprior to immune system development. This could be a way to make humancells, such as blood, in large quantities in animals or it could be usedas a way to correct human embryo genetic defects by transplanting cellsthat make the correct protein or enzyme.

The present invention also provides for methods of using the DPMSCs forgene therapy in an individual in need of therapeutic treatment,involving genetically altering the cells by introducing into the cell anisolated pre-selected DNA encoding a desired gene product, expanding thecells in culture, and introducing the cells into the body of theindividual to produce the desired gene product. Until now, human cellsused for gene therapy have been essentially limited to bone marrow andskin cells, because other types of cells could not be extracted from thebody, grown in culture, genetically altered, then successfullyreimplanted into the patient from whom the tissue was taken. See, forexample, Anderson, W. F., Nature (1998) 392: 30; Anderson, W. F.,Scientific American (1995) 273: 15; Anderson, W. F. Science (1992) 256:808-813). DPMSCs of the present invention can be extracted and isolatedfrom the body, grown in culture in the undifferentiated state or inducedto differentiate in culture, and genetically altered using a variety oftechniques, especially viral transduction. Uptake and expression ofgenetic material is demonstrable, and expression of foreign DNA isstable throughout development. Retroviral and other vectors forinserting foreign DNA into stem cells are known to those of skill in theart. See, e.g., Mochizuki, H., et al., J. Virol (1998) 72(11):8873-8883; Robbins, P., et al., J. Virol. (1997) 71(12): 9466-9474;Bierhuizen, M., et al., Blood (1997) 90(9): 3304-3315; Douglas, J., etal., Hum. Gene Ther. (1999) 10(6): 935-945; Zhang, G., et al., Biochem.Biophys. Res. Commun. (1996) 227(3): 707-711). Once transduced using aretroviral vector, enhanced green fluorescent protein (eGFP) expressionpersists in terminally differentiated muscle cells, and endotheliumderived from the isolated DPMSCs, demonstrating that expression ofretroviral vectors introduced into DPMSC persists throughoutdifferentiation.

Hematopoietic stem cells, although limited in differentiation potential,demonstrate utility for gene therapy (see Kohn, D. B., Curr. Opin.Pediatr. (1995) 7: 56-63). The cells of the present invention provide awider range of differentiated cell types which can retain transduced ortransfected DNA when terminally differentiated, as demonstrated by thefact that terminally differentiated muscle cells, endothelium, and c-Kitpositive cells retained enhanced green fluorescent protein expressionalthough the retroviral vector had been introduced into theundifferentiated stem cell.

DPMSCs of the present invention provide other advantages overhematopoietic stem cells for gene therapy, as well. Stem cells of thepresent invention are relatively easy to isolate from bone marrowaspirates obtained under local anesthesia, easy to expand in culture,and easy to transfect with exogenous genes. Adequate numbers ofhematopoietic stem cells for the same purpose must be isolated from atleast one liter of marrow and the cells are difficult to expand inculture (see Prockop, D. J., Science (1997) 276: 71-74).

Candidate genes for gene therapy include, for example, genes encodingApolipoprotein E (which has been correlated with risk for Alzheimer'sdisease and cardiovascular disease), MTHFR (variants of which have beenassociated with increased homocysteine levels and risk of stroke),Factor V (which has been correlated with risk of thrombosis), ACE(variants of which have been correlated with risk of heart disease),CKR-5 (which has been associated with resistance to HIV), HPRT(hypoxanthine-guanine phosphoribosyl transferase, the absence of whichresults in Lesch-Nyhan disease), PNP (purine nucleoside phosphorylase,the absence of which results in severe immunodeficiency disease), ADA(adenosine deaminase, the absence of which results in severe combinedimmunodeficiency disease), p21 (which has been proposed as a candidategene for treatment for ataxia telangiectasia), p47 (the absence of whichis correlated with lack of oxidase activity in neutrophils of patientswith chronic granulomatous disease, GenBank accession number M55067 andM38755), Rb (the retinoblastoma susceptibility gene associated withtumor formation, GenBank accession number M15400), KVLQT1 (a potassiumchannel protein, with aberrant forms associated with cardiacarrhythmias, GenBank accession number U40990), the dystrophin gene(associated with Duchenne muscular dystrophy, GenBank accession numbersM18533, M17154, and M18026), CFTR (the transmembrane conductanceregulator associated with cystic fibrosis, GenBank accession numberM28668), phosphatidylinositol 3-kinase (associated with ataxiatelangiectasia, GenBank accession number U26455), and VHL (loss ormutation of the protein is associated with Von-Hippel Lindau disease:Latif, F., et al., Science (1993) 260: 1317-1320). Other diseases whichcan be treated effectively using these genetically-altered cellsinclude, Factor IX deficiency, adenosine deaminase deficiency(associated with severe combined immunodeficiency disease, or SCIDS),and diabetes, and deficiencies in glucocerebrosidase α-iduronidase.

These novel genes can be driven by an inducible promoter so that levelsof enzyme can be regulated. These inducible promoter systems may includea mutated ligand binding domain of the human estrogen receptor (ER)attached to the protein to be produced. This would require that theindividual ingests tamoxifen to allow expression of the protein.Alternatives are tetracyclin on or off systems, RU486, and a rapamycininducible system. An additional method to obtain relative selectiveexpression is to use tissue specific promoters. For instance in thebrain, one can introduce a transgene driven by the neuron-specificenolase promoter (Ad-NSE) or the glial fibrillary acidic proteinpromoter (GFAP) promoter, which will allow almost exclusive expressionin brain tissue. Likewise, endothelial expression only may be obtainedby using the Tec promoter or the VE-cadherin promoter.

Genetically altered DPMSCs can be introduced locally or infusedsystemically. Human stem cells with more limited differentiationpotential, when transfected with a gene for factor IX, secrete theprotein for at least 8 weeks after systemic infusion into SCID mice.See, e.g., Keating, A., et al., Blood (1996) 88: 3921. DPMSCs of thepresent invention, having a broader differentiation potential than othernon-embryonic stem cell, provide an added advantage for systemic orlocal administration, because they can migrate to a variety of tissues,where cytokines, growth factors, and other factors inducedifferentiation of the cell. The differentiated cell, now a part of thesurrounding tissue, retains its ability to produce the protein productof the introduced gene.

In Parkinson's disease, for example, clinical trials have shown thatmesencephalic dopamine neurons obtained from human embryo cadavers cansurvive and function in the brains of patients with Parkinson's disease.PET scans have indicated that _([18F])fluorodopa uptake in the areaaround the cell graft is increased after transplantation, and remains sofor at least six years in some patients. See, e.g., Dunnett, S, and A.Biorklund, Nature (1999) 399 (Suppl.) A32-A-39; Lindvall, O., NatureBiotech. (1999)17: 635-636; Wagner, J., et al., Nature Biotech. (1999)17: 653-659. Unlike the embryonic cells, isolated DPMSCs as described bythe present invention provide a ready supply of cells for transplant,yet maintain the differentiation potential that makes embryonic celltransplant therapy an attractive alternative for disease treatment.

For AIDS therapy, DPMSCs of the present invention can be geneticallyengineered to produce Rev M10, a transdominant negative mutant of Revthat blocks the function of a wild-type Rev produced in HIV-infectedcells. See, e.g., Bevec, D. et al., Proc. Natl. Acad. Sci. USA (1992)89: 9870-9874; Ranga, U., et al., Proc. Natl. Acad. Sci. USA (1998)95(3): 1201-1206. Once induced to differentiate into hematopoieticlineage cells and introduced into the patient, DPMSCs can repopulate theHIV-infected patient's depleted T cell supply. Since the geneticallyaltered cells possess the mutant Rev M110, they will most likely beresistant to the lethal effects of infection by most strains of HIV.

Genetically altered DPMSCs can also be encapsulated in an inert carrierto allow the cells to be protected from the host immune system whileproducing the secreted protein. Techniques for microencapsulation ofcells are known to those of skill in the art, see, for example, Chang,P., et al., Trends in Biotech. (1999) 17(2): 78-83). Materials formicroencapsulation of cells include, for example, polymer capsules,alginate-poly-L-lysine-alginate microcapsules, barium poly-L-lysinealginate capsules, barium alginate capsules,polyacrylonitrile/polyvinylchloride (PAN/PVC) hollow fibers, andpolyethersulfone (PES) hollow fibers. U.S. Pat. No. 5,639,275 (Baetge,E., et al.), for example, describes improved devices and methods forlong-term, stable expression of a biologically active molecule using abiocompatible capsule containing genetically engineered cells. Suchbiocompatible immunoisolatory capsules, in combination with the DPMSCsof the present invention, provide a method for treating a number ofphysiologic disorders, including, for example, diabetes and Parkinson'sdisease.

In the diabetic patient, for example, heterologous stem cells which havebeen genetically altered to produce insulin at physiologicallytherapeutic levels can be encapsulated for delivery within the patient'stissues. Alternately, autologous stem cells can be derived from thepatient's own bone marrow aspirate for transduction with a retroviralvector as previously described. Once genetically altered to producephysiologically therapeutic levels of insulin, these cells can beencapsulated as described by Chang or Baetge and introduced into thepatient's tissues where they remain to produce insulin for extendedperiods of time.

Another advantage of microencapsulation of cells of the presentinvention is the opportunity to incorporate into the microcapsule avariety of cells, each producing a biologically therapeutic molecule.DPMSCs of the present invention can be induced to differentiate intomultiple distinct lineages, each of which can be genetically altered toproduce therapeutically effective levels of biologically activemolecules. DPMSCs carrying different genetic elements can beencapsulated together to produce a variety of biologically activemolecules.

DPMSCs of the present invention can be genetically altered ex vivo toexpress one or more desired gene products. The DPMSCs can then bescreened or selected ex vivo to identify those cells which have beensuccessfully altered, and these cells can be reintroduced into theindividual, either locally or systemically. Alternately, DPMSCs can begenetically altered and cultured to induce differentiation to form aspecific cell lineage for transplant. In either case, the transplantedDPMSCs provide a stably-transfected source of cells that can express adesired gene product. Especially where the patient's own bone marrowaspirate is the source of the DPMSCs, this method provides animmunologically safe method for producing transplant cells. The methodcan be used for treatment of diabetes, cardiac myopathy,neurodegenerative disease, and adenosine deaminase deficiency, to nameonly a few of a multitude of examples. In diabetes, for example, DPMSCscan be isolated, genetically altered to produce insulin, thentransplanted into the patient suffering from the disease. Where thedisease is associated with autoimmunity, DPMSCs can be geneticallyaltered to express either an altered MHC or no MHC in order to avoidimmune surveillance. Suppression of MHC expression in transplantedpancreatic islet cells has been successfully performed using anadenoviral vector expressing the E3 region of the viral genome. Cells ofthe present invention can be stably transfected or transduced, as theinventors have demonstrated, and can therefore provide a more permanentsource of insulin for transplant into a diabetic patient.

Donor DPMSCs, particularly if genetically altered to alter MHCexpression, and autologous DPMSCs, if genetically altered to express thedesired hemoglobin gene products, can be especially effective in celltherapy for the treatment of sickle cell anemia and thalassemia.

Methods for Genetically Altering DPMSCs

Cells isolated by the method described herein can be geneticallymodified by introducing DNA or RNA into the cell by a variety of methodsknown to those of skill in the art. These methods are generally groupedinto four major categories: (1) viral transfer, including the use of DNAor RNA viral vectors, such as retroviruses (including lentiviruses),Simian virus 40 (SV40), adenovirus, Sindbis virus, and bovinepapillomavirus for example; (2) chemical transfer, including calciumphosphate transfection and DEAE dextran transfection methods; (3)membrane fusion transfer, using DNA-loaded membranous vesicles such asliposomes, red blood cell ghosts, and protoplasts, for example; and (4)physical transfer techniques, such as microinjection, electroporation,or direct “naked” DNA transfer.

DPMSCs can be genetically altered by insertion of pre-selected isolatedDNA, by substitution of a segment of the cellular genome withpre-selected isolated DNA, or by deletion of or inactivation of at leasta portion of the cellular genome of the cell. Deletion or inactivationof at least a portion of the cellular genome can be accomplished by avariety of means, including but not limited to genetic recombination, byantisense technology (which can include the use of peptide nucleicacids, or PNAs), or by ribozyme technology, for example. Insertion ofone or more pre-selected DNA sequences can be accomplished by homologousrecombination or by viral integration into the host cell genome. Thedesired gene sequence can also be incorporated into the cell,particularly into its nucleus, using a plasmid expression vector and anuclear localization sequence. Methods for directing polynucleotides tothe nucleus have been described in the art. The genetic material can beintroduced using promoters that will allow for the gene of interest tobe positively or negatively induced using certain chemicals/drugs, to beeliminated following administration of a given drug/chemical, or can betagged to allow induction by chemicals (including but not limited to thetamoxifen responsive mutated estrogen receptor) expression in specificcell compartments (including but not limited to the cell membrane).

Homologous Recombination

Calcium phosphate transfection, which relies on precipitates of plasmidDNA/calcium ions, can be used to introduce plasmid DNA containing atarget gene or polynucleotide into isolated or cultured DPMSCs. Briefly,plasmid DNA is mixed into a solution of calcium chloride, then added toa solution which has been phosphate-buffered. Once a precipitate hasformed, the solution is added directly to cultured cells. Treatment withDMSO or glycerol can be used to improve transfection efficiency, andlevels of stable transfectants can be improved usingbis-hydroxyethylamino ethanesulfonate (BES). Calcium phosphatetransfection systems are commercially available (e.g., ProFection® fromPromega Corp., Madison, Wis.).

DEAE-dextran transfection, which is also known to those of skill in theart, may be preferred over calcium phosphate transfection wheretransient transfection is desired, as it is often more efficient.

Since the cells of the present invention are isolated cells,microinjection can be particularly effective for transferring geneticmaterial into the cells. Briefly, cells are placed onto the stage of alight microscope. With the aid of the magnification provided by themicroscope, a glass micropipette is guided into the nucleus to injectDNA or RNA. This method is advantageous because it provides delivery ofthe desired genetic material directly to the nucleus, avoiding bothcytoplasmic and lysosomal degradation of the injected polynucleotide.This technique has been used effectively to accomplish germlinemodification in transgenic animals.

Cells of the present invention can also be genetically modified usingelectroporation. The target DNA or RNA is added to a suspension ofcultured cells. The DNA/RNA-cell suspension is placed between twoelectrodes and subjected to an electrical pulse, causing a transientpermeability in the cell's outer membrane that is manifested by theappearance of pores across the membrane. The target polynucleotideenters the cell through the open pores in the membrane, and when theelectric field is discontinued, the pores close in approximately one to30 minutes.

Liposomal delivery of DNA or RNA to genetically modify the cells can beperformed using cationic liposomes, which form a stable complex with thepolynucleotide. For stabilization of the liposome complex, dioleoylphosphatidylethanolamine (DOPE) or dioleoyl phosphatidylcholine (DOPC)can be added. A recommended reagent for liposomal transfer isLipofectin® (Life Technologies, Inc.), which is commercially available.Lipofectin®, for example, is a mixture of the cationic lipidN-[1-(2,3-dioleyloyx)propyl]-N—N—N-trimethyl ammonia chloride and DOPE.Delivery of linear DNA, plasmid DNA, or RNA can be accomplished eitherin vitro or in vivo using liposomal delivery, which may be a preferredmethod due to the fact that liposomes can carry larger pieces of DNA,can generally protect the polynucleotide from degradation, and can betargeted to specific cells or tissues. A number of other deliverysystems relying on liposomal technologies are also commerciallyavailable, including Effectene™ (Qiagen), DOTAP (Roche MolecularBiochemicals), FuGene 6™ (Roche Molecular Biochemicals), andTransfectam® (Promega). Cationic lipid-mediated gene transfer efficiencycan be enhanced by incorporating purified viral or cellular envelopecomponents, such as the purified G glycoprotein of the vesicularstomatitis virus envelope (VSV-G), in the method of Abe, A., et al. (J.Virol. (1998) 72: 6159 6163).

Gene transfer techniques which have been shown effective for delivery ofDNA into primary and established mammalian cell lines usinglipopolyamine-coated DNA can be used to introduce target DNA intoDPMSCs. This technique is generally described by Loeffler, J. and Behr,J., Methods in Enzymology (1993) 217: 599-618.

Naked plasmid DNA can be injected directly into a tissue mass formed ofdifferentiated cells from the isolated DPMSCs. This technique has beenshown to be effective in transferring plasmid DNA to skeletal muscletissue, where expression in mouse skeletal muscle has been observed formore than 19 months following a single intramuscular injection. Morerapidly dividing cells take up naked plasmid DNA more efficiently.Therefore, it is advantageous to stimulate cell division prior totreatment with plasmid DNA.

Microprojectile gene transfer can also be used to transfer genes intoDPMSCs either in vitro or in vivo. The basic procedure formicroprojectile gene transfer was described by J. Wolff in GeneTherapeutics (1994) at page 195. Briefly, plasmid DNA encoding a targetgene is coated onto microbeads, usually 1-3 micron sized gold ortungsten particles. The coated particles are placed onto a carrier sheetinserted above a discharge chamber. Once discharged, the carrier sheetis accelerated toward a retaining screen. The retaining screen forms abarrier which stops further movement of the carrier sheet while allowingthe polynucleotide-coated particles to be propelled, usually by a heliumstream, toward a target surface, such as a tissue mass formed ofdifferentiated DPMSCs. Microparticle injection techniques have beendescribed previously, and methods are known to those of skill in the art(see Johnston, S. A., et al., Genet. Eng. (NY) (1993) 15: 225-236;Williams, R. S., et al., Proc. Natl. Acad. Sci. USA (1991) 88:2726-2730; Yang, N. S., et al., Proc. Natl. Acad. Sci. USA (1990) 87:9568-9572).

Signal peptides can be attached to plasmid DNA, as described bySebestyen, et al. (Nature Biotech. (1998) 16: 80-85), to direct the DNAto the nucleus for more efficient expression.

Viral vectors are used to genetically alter DPMSCs of the presentinvention and their progeny. Viral vectors are used, as are the physicalmethods previously described, to deliver one or more target genes,polynucleotides, antisense molecules, or ribozyme sequences, forexample, into the cells. Viral vectors and methods for using them todeliver DNA to cells are well known to those of skill in the art.Examples of viral vectors which can be used to genetically alter thecells of the present invention include, but are not limited to,adenoviral vectors, adeno-associated viral vectors, retroviral vectors(including lentiviral vectors), alphaviral vectors (e.g., Sindbisvectors), and herpes virus vectors.

Retroviral vectors are effective for transducing rapidly-dividing cells,although a number of retroviral vectors have been developed toeffectively transfer DNA into non-dividing cells as well (Mochizuki, H.,et al., J. Virol. (1998) 72: 8873-8883). Packaging cell lines forretroviral vectors are known to those of skill in the art. Packagingcell lines provide the viral proteins needed for capsid production andvirion maturation of the viral vector. Generally, these include the gag,pol, and env retroviral genes. An appropriate packaging cell line ischosen from among the known cell lines to produce a retroviral vectorwhich is ecotropic, xenotropic, or amphotropic, providing a degree ofspecificity for retroviral vector systems.

A retroviral DNA vector is generally used with the packaging cell lineto produce the desired target sequence/vector combination within thecells. Briefly, a retroviral DNA vector is a plasmid DNA which containstwo retroviral LTRs positioned about a multicloning site and SV40promoter so that a first LTR is located 5 to the SV40 promoter, which isoperationally linked to the target gene sequence cloned into themulticloning site, followed by a 3 second LTR. Once formed, theretroviral DNA vector can be transferred into the packaging cell lineusing calcium phosphate-mediated transfection, as previously described.Following approximately 48 hours of virus production, the viral vector,now containing the target gene sequence, is harvested.

Targeting of retroviral vectors to specific cell types was demonstratedby Martin, F., et al., (J. Virol. (1999) 73: 6923-6929), who usedsingle-chain variable fragment antibody directed against the surfaceglycoprotein high-molecular-weight melanoma-associated antigen fused tothe amphotropic murine leukemia virus envelope to target the vector todelivery the target gene to melanoma cells. Where targeted delivery isdesired, as, for example, when differentiated cells are the desiredobjects for genetic alteration, retroviral vectors fused to antibodyfragments directed to the specific markers expressed by each celllineage differentiated from the DPMSCs of the present invention can beused to target delivery to those cells.

Lentiviral vectors are also used to genetically alter cells of theinvention. Many such vectors have been described in the literature andare known to those of skill in the art. Salmons, B. and Gunzburg, W. H.,“Targeting of Retroviral Vectors for Gene Therapy,” Hum. Gene Therapy(1993) 4: 129-141. These vectors have been effective for geneticallyaltering human hematopoietic stem cells (Sutton, R., et al., J. Virol.(1998) 72: 5781-5788). Packaging cell lines have been described forlentivirus vectors (see Kafri, T., et al., J. Virol. (1999) 73: 576-584;Dull, T., et al., J. Virol. (1998) 72: 8463-8471).

Recombinant herpes viruses, such as herpes simplex virus type I (HSV-1)have been used successfully to target DNA delivery to cells expressingthe erythropoietin receptor (Laquerre, S., et al., J. Virol. (1998) 72:9683-9697). These vectors can also be used to genetically alter thecells of the present invention, which the inventors have demonstrated tobe stably transduced by a viral vector.

Adenoviral vectors have high transduction efficiency, can incorporateDNA inserts up to 8 Kb, and can infect both replicating anddifferentiated cells. A number of adenoviral vectors have been describedin the literature and are known to those of skill in the art (see, forexample, Davidson, B. L., et al., Nature Genetics (1993) 3: 219-223;Wagner, E., et al., Proc. Natl. Acad. Sci. USA (1992) 89: 6099-6103).Methods for inserting target DNA into an adenovirus vector are known tothose of skill in the art of gene therapy, as are methods for usingrecombinant adenoviral vectors to introduce target DNA into specificcell types (see Wold, W., Adenovirus Methods and Protocols, HumanaMethods in Molecular Medicine (1998), Blackwell Science, Ltd.). Bindingaffinity for certain cell types has been demonstrated by modification ofthe viral vector fiber sequence. Adenovirus vector systems have beendescribed which permit regulated protein expression in gene transfer(Molin, M., et al., J. Virol. (1998) 72: 8358-8361). A system has alsobeen described for propagating adenoviral vectors with geneticallymodified receptor specificities to provide transductional targeting tospecific cell types (Douglas, J., et al., Nature Biotech. (1999) 17:470-475). Recently described ovine adenovirus vectors even address thepotential for interference with successful gene transfer by preexistinghumoral immunity (Hofmann, C., et al., J. Virol. (1999) 73: 6930-6936).

Adenovirus vectors are also available which provide targeted genetransfer and stable gene expression using molecular conjugate vectors,constructed by condensing plasmid DNA containing the target gene withpolylysine, with the polylysine linked to a replication-incompetentadenovirus. (Schwarzenberger, P., et al., J. Virol. (1997) 71:8563-8571.)

Alphavirus vectors, particularly the Sindbis virus vectors, are alsoavailable for transducing the cells of the present invention. Thesevectors are commercially available (Invitrogen, Carlsbad, Calif.) andhave been described in, for example, U.S. Pat. No. 5,843,723, as well asby Xiong, C., et al., Science (1989) 243: 1188-1191; Bredenbeek, P. J.,et al., J. Virol. (1993) 67: 6439-6446; and Frolov, I., et al., Proc.Natl. Acad. Sci. USA (1996) 93: 11371-11377.

The stem cells of the present invention can also be used for tissuerepair. The inventors have demonstrated that DPMSCs of the presentinvention differentiate to form a number of cell types, includingfibroblasts, osteoblasts, (skeletal muscle, smooth muscle, cardiacmuscle) cells. For example, DPMSCs induced to differentiate intoosteoblasts, by the method previously described herein, can be implantedinto bone to enhance the repair process, to reinforce weakened bone, orto resurface joints.

Matrices are also used to deliver cells of the present invention tospecific anatomic sites, where particular growth factors incorporatedinto the matrix, or encoded on plasmids incorporated into the matrix foruptake by the cells, can be used to direct the growth of the initialcell population. DNA can be incorporated within pores of the matrix, forexample, during the foaming process used in the formation of certainpolymer matrices. As the polymer used in the foaming process expands, itentraps the DNA within the pores, allowing controlled and sustainedrelease of plasmid DNA. Such a method of matrix preparation is describedby Shea, et al., in Nature Biotechnology (1999) 17: 551-554.

Plasmid DNA encoding cytokines, growth factors, or hormones can betrapped within a polymer gene-activated matrix carrier, as described byBonadio, J., et al., Nature Medicine (1999) July 5(7):753-759. Thebiodegradable polymer is then implanted near a broken bone, for example,where DPMSCs are implanted and take up the DNA, which causes the DPMSCsto produce a high local concentration of the cytokine, growth factor, orhormone, accelerating healing of the damaged tissue.

Cells provided by the present invention, or DPMSCs isolated by themethod of the present invention, can be used to produce tissues ororgans for transplantation. Oberpenning, et al. (Nature Biotechnology(1999) 17: 149-155) reported the formation of a working bladder byculturing muscle cells from the exterior canine bladder and lining cellsfrom the interior of the canine bladder, preparing sheets of tissue fromthese cultures, and coating a small polymer sphere with muscle cells onthe outside and lining cells on the inside. The sphere was then insertedinto a dog's urinary system, where it began to function as a bladder.Nicklason, et al., Science (1999) 284: 489-493, reported the productionof lengths of vascular graft material from cultured smooth muscle andendothelial cells. Other methods for forming tissue layers from culturedcells are known to those of skill in the art (see, for example, Vacanti,et al., U.S. Pat. No. 5,855,610). These methods can be especiallyeffective when used in combination with cells of the present invention,which have a broader range of differentiation than previously-describednon-embryonic stem cells.

DPMSCs of the present invention can be used to repopulate heart musclecells by either direct injection into the area of tissue damage or bysystemic injection, allowing the cells to home to the cardiac tissues.This method can be particularly effective if combined with angiogenesis.Both the methods of injection and methods for promoting angiogenesis areknown to those of skill in the art. The DPMSCs of the present inventionprovide a broader differentiation range to provide a more varied sourceof cells for cardiac or other tissue repair utilizing these techniques.

DPMSCs of the present invention are also useful, for example, for thepurpose of repopulating the bone marrow after high dose chemotherapy.Prior to chemotherapy, a DPMSCs are obtained from the patient. Stemcells are isolated by the method of the present invention, and are grownin culture and induced to differentiate. A mixture of differentiated andundifferentiated cells is then reintroduced into the patient's bonemarrow space. Clinical trials are currently underway using hematopoieticstem cells for this purpose. The DPMSCs of the present invention,however, provide the additional benefit of further differentiation toform cells that can replace those damaged by chemotherapy in othertissues as well as in bone marrow.

Alternatively, the method described by Lawman, et al. (WO 98/42838) canbe used to change the histocompatibility antigen of stem cells from anallogeneic donor or donors. Using this method, panels of available bonemarrow transplants can be generated for preparation of frozen stocks,storage, and administration to patients who are unable, as in leukemiapatients, for example, to provide their own bone marrow forreconstitution.

Re-population of a patient's immune system cells or blood cells can beaccomplished, for example, by isolating autologous stem cells from thepatient, culturing those cells to expand the population, thenreintroducing the cells into the patient. This method can beparticularly effective where the immune system or bone marrow cells mustbe depleted by radiation and/or chemotherapy for therapeutic purposes,such as in the case, for example, of patients diagnosed with multiplemyeloma, non-Hodgkins lymphoma, autoimmune disease, or solid tumorcancers.

For the treatment of leukemias, autoimmune disease, or genetic diseasessuch as sickle cell anemia or thalassemia, re-population of thepatient's blood or immune system cells with allogeneic cells of thepresent invention, or isolated by the method of the present invention,can be performed, particularly when the histocompatibility antigen hasbeen altered in the manner described by Lawman, et al. (WO 98/42838).

For the purposes described herein, either autologous or allogeneicDPMSCs of the present invention can be administered to a patient, eitherin differentiated or undifferentiated form, genetically altered orunaltered, by direct injection to a tissue site, systemically, on oraround the surface of an acceptable matrix, or in combination with apharmaceutically acceptable carrier.

DPMSCs Provide a Model System for Studying Differentiation Pathways:

Yet another use of the population of DPMSCs of the invention is as aresearch tool. Cells of the present invention are useful for furtherresearch into developmental processes, as well. Ruley, et al. (WO98/40468), for example, have described vectors and methods forinhibiting expression of specific genes, as well as obtaining the DNAsequences of those inhibited genes. Cells of the present invention canbe treated with the vectors such as those described by Ruley, whichinhibit the expression of genes that can be identified by DNA sequenceanalysis. The cells can then be induced to differentiate and the effectsof the altered genotype/phenotype can be characterized.

Hahn, et al. (Nature (1999) 400: 464468) demonstrated, for example, thatnormal human epithelial fibroblast cells can be induced to undergotumorigenic conversion when a combination of genes, previouslycorrelated with cancer, were introduced into the cells.

Control of gene expression using vectors containing inducible expressionelements provides a method for studying the effects of certain geneproducts upon cell differentiation. Inducible expression systems areknown to those of skill in the art. One such system is theecdysone-inducible system described by No, D., et al. Proc. Natl. Acad.Sci. USA (1996) 93: 3346-3351.

DPMSCs can be used to study the effects of specific genetic alterations,toxic substances, chemotherapeutic agents, or other agents on thedevelopmental pathways. Tissue culture techniques known to those ofskill in the art allow mass culture of hundreds of thousands of cellsamples from different individuals, providing an opportunity to performrapid screening of compounds suspected to be, for example, teratogenicor mutagenic.

For studying developmental pathways, DPMSCs can be treated with specificgrowth factors, cytokines, or other agents, including suspectedteratogenic chemicals. DPMSCs can also be genetically modified usingmethods and vectors previously described. Furthermore, DPMSCs can bealtered using antisense technology or treatment with proteins introducedinto the cell to alter expression of native gene sequences. Signalpeptide sequences, for example, can be used to introduce desiredpeptides or polypeptides into the cells. A particularly effectivetechnique for introducing polypeptides and proteins into the cell hasbeen described by Rojas, et al., in Nature Biotechnology (1998) 16:370-375. This method produces a polypeptide or protein product that canbe introduced into the culture media and translocated across the cellmembrane to the interior of the cell. Any number of proteins can be usedin this manner to determine the effect of the target protein upon thedifferentiation of the cell. Alternately, the technique described byPhelan et al. (Nature Biotech. (1998) 16: 440-443) can be used to linkthe herpes virus protein VP22 to a functional protein for import intothe cell.

Cells of the present invention can also be genetically engineered, bythe introduction of foreign DNA or by silencing or excising genomic DNA,to produce differentiated cells with a defective phenotype in order totest the effectiveness of potential chemotherapeutic agents or genetherapy vectors.

DPMSCs Provide a Variety of Differentiated and Undifferentiated CulturedCell Types for High-Throughput Screening

DPMSCs of the present invention can be cultured in, for example, 96-wellor other multi-well culture plates to provide a system forhigh-throughput screening of, for example, target cytokines, chemokines,growth factors, or pharmaceutical compositions in pharmacogenomics orpharmacogenetics. The DPMSCs of the present invention provide a uniquesystem in which cells can be differentiated to form specific celllineages from the same individual. Unlike most primary cultures, thesecells can be maintained in culture and can be studied over time.Multiple cultures of cells from the same individual and from differentindividuals can be treated with the factor of interest to determinewhether differences exist in the effect of the cellular factor oncertain types of differentiated cells with the same genetic makeup or onsimilar types of cells from genetically different individuals.

Cytokines, chemokines, pharmaceutical compositions and growth factors,for example, can therefore be screened in a timely and cost-effectivemanner to more clearly elucidate their effects. Cells isolated from alarge population of individuals and characterized in terms of presenceor absence of genetic polymorphisms, particularly single nucleotidepolymorphisms, can be stored in cell culture banks for use in a varietyof screening techniques. For example, dental pulp marrow similar cellsfrom a statistically significant population of individuals, which can bedetermined according to methods known to those of skill in the art,provide an ideal system for high-throughput screening to identifypolymorphisms associated with increased positive or negative response toa range of substances such as, for example, pharmaceutical compositions,vaccine preparations, cytotoxic chemicals, mutagens, cytokines,chemokines, growth factors, hormones, inhibitory compounds,chemotherapeutic agents, and a host of other compounds or factors.Information obtained from such studies has broad implication for thetreatment of infectious disease, cancer, and a number of metabolicdiseases.

In the method of using DPMSCs to characterize cellular responses tobiologic or pharmacologic agents, or combinatorial libraries of suchagents, DPMSCs are isolated from a statistically significant populationof individuals, culture expanded, and contacted with one or morebiologic or pharmacologic agents. DPMSCs can be induced todifferentiate, where differentiated cells are the desired target for acertain biologic or pharmacologic agent, either prior to or afterculture expansion. By comparing the one or more cellular responses ofthe DPMSC cultures from individuals in the statistically significantpopulation, the effects of the biologic or pharmacologic agent can bedetermined. Alternately, genetically identical DPMSCs, or cellsdifferentiated therefrom, can be used to screen separate compounds, suchas compounds of a combinatorial library. Gene expression systems for usein combination with cell-based high-throughput screening have beendescribed (see Jayawickreme, C. and Kost, T., Curr. Opin. Biotechnol.(1997) Oct. 8, 5: 629-634). A high volume screening technique used toidentify inhibitors of endothelial cell activation has been described byRice, et al., which utilizes a cell culture system for primary humanumbilical vein endothelial cells. (Rice, et al., Anal. Biochem. (1996)241: 254-259.) The cells of the present invention provide a variety ofcell types, both terminally differentiated and undifferentiated, forhigh-throughput screening techniques used to identify a multitude oftarget biologic or pharmacologic agents. Importantly, the cells of thepresent invention provide a source of cultured cells from a variety ofgenetically diverse individuals who may respond differently to biologicand pharmacologic agents.

DPMSCs and Genetic Profiling

Genetic variation can have indirect and direct effects on diseasesusceptibility. In a direct case, even a single nucleotide change,resulting in a single nucleotide polymorphism (SNP), can alter the aminoacid sequence of a protein and directly contribute to disease or diseasesusceptibility. Functional alteration in the resulting protein can oftenbe detected in vitro. For example, certain APO-lipoprotein E genotypeshave been associated with onset and progression of Alzheimer's diseasein some individuals.

DNA sequence anomalies can be detected by dynamic-allele specifichybridization, DNA chip technologies, and other techniques known tothose of skill in the art. Protein coding regions have been estimated torepresent only about 3% of the human genome, and it has been estimatedthat there are perhaps 200,000 to 400,000 common SNPs located in codingregions.

Previous investigational designs using SNP-associated genetic analysishave involved obtaining samples for genetic analysis from a large numberof individuals for whom phenotypic characterization can be performed.Unfortunately, genetic correlations obtained in this manner are limitedto identification of specific polymorphisms associated with readilyidentifiable phenotypes, and do not provide further information into theunderlying cause of the disease.

DPMSCs of the present invention can provide the necessary element tobridge the gap between identification of a genetic element associatedwith a disease and the ultimate phenotypic expression noted in a personsuffering from the disease. Briefly, DPMSCs are isolated from astatistically significant population of individuals from whom phenotypicdata can be obtained (see Collins, et al., Genome Research (1998)December, 8(12):1229-1231). These DPMSC samples are then culturedexpanded and subcultures of the cells are stored as frozen stocks, whichcan be used to provide cultures for subsequent developmental studies.From the expanded population of cells, multiple genetic analyses can beperformed to identify genetic polymorphisms. For example, singlenucleotide polymorphisms can be identified in a large sample populationin a relatively short period of time using current techniques, such asDNA chip technology, known to those of skill in the art (Wang, D., etal., Science (1998) 280: 1077-1082; Chee, M., et al., Science (1996)274: 610-614; Cargill, M., et al., Nature Genetics (1999) 22: 231-238;Gilles, P., et al., Nature Biotechnology (1999) 17: 365-370; Zhao, L.P., et al., Am. J. Human Genet. (1998) 63: 225-240). Techniques for SNPanalysis have also been described by Syvanen (Syvanen, A., Hum. Mut.(1999) 13: 1-10), Xiong (Xiong, M. and L. Jin, Am. J. Hum. Genet. (1999)64: 629-640), Gu (Gu, Z., et al., Human Mutation (1998) 12: 221-225),Collins (Collins, F., et al., Science (1997) 278: 1580-1581), Howell(Howell, W., et al., Nature Biotechnology (1999) 17: 87-88), Buetow(Buetow, K., et al., Nature Genetics (1999) 21: 323-325), and Hoogendoom(Hoogendoom, B., et al., Hum. Genet. (1999) 104: 89-93).

When certain polymorphisms are associated with a particular diseasephenotype, cells from individuals identified as carriers of thepolymorphism can be studied for developmental anomalies, using cellsfrom non-carriers as a control. DPMSCs of the present invention providean experimental system for studying developmental anomalies associatedwith particular genetic disease presentations, particularly, since theycan be induced to differentiate, using certain methods described hereinand certain other methods known to those of skill in the art, to formparticular cell types. For example, where a specific SNP is associatedwith a neurodegenerative disorder, both undifferentiated DPMSCs andDPMSCs differentiated to form neuronal precursors, glial cells, or othercells of neural origin, can be used to characterize the cellular effectsof the polymorphism. Cells exhibiting certain polymorphisms can befollowed during the differentiation process to identify genetic elementswhich affect drug sensitivity, chemokine and cytokine response, responseto growth factors, hormones, and inhibitors, as well as responses tochanges in receptor expression and/or function. This information can beinvaluable in designing treatment methodologies for diseases of geneticorigin or for which there is a genetic predisposition.

In the present method of using DPMSCs to identify genetic polymorphismsassociated with physiologic abnormalities, DPMSCs are isolated from astatistically significant population of individuals from whom phenotypicdata can be obtained (a statistically significant population beingdefined by those of skill in the art as a population size sufficient toinclude members with at least one genetic polymorphism) and cultureexpanded to establish DPMSC cultures. DNA from the cultured cells isthen used to identify genetic polymorphisms in the cultured DPMSCs fromthe population, and the cells are induced to differentiate. Aberrantmetabolic processes associated with particular genetic polymorphisms areidentified and characterized by comparing the differentiation patternsexhibited by DPMSCs having a normal genotype with differentiationpatterns exhibited by DPMSCs having an identified genetic polymorphismor response to putative drugs.

DPMSCs Provide Safer Vaccine Delivery

DPMSCs cells of the present invention can also be used asantigen-presenting cells when genetically altered to produce anantigenic protein. Using multiple altered autologous or allogeneicprogenitor cells, for example, and providing the progenitor cells of thepresent invention in combination with plasmids embedded in abiodegradable matrix for extended release to transfect the accompanyingcells, an immune response can be elicited to one or multiple antigens,potentially improving the ultimate effect of the immune response bysequential release of antigen-presenting cells. It is known in the artthat multiple administrations of some antigens over an extended periodof time produce a heightened immune response upon ultimate antigenicchallenge. Alternately, DPMSCs can be used as antigen-presenting cells,in the method of Zhang, et al. (Nature Biotechnology (1998) 1:1045-1049), to induce T-cell tolerance to specific antigen.

Many current vaccine preparations incorporate added chemicals and othersubstances, such as antibiotics (to prevent the growth of bacteria invaccine cultures), aluminum (adjuvant), formaldehyde (to inactivatebacterial products for toxoid vaccines), monosodium glutamate(stabilizer), egg protein (component of vaccines prepared usingembryonated chicken eggs), sulfites (stabilizer), and thimerosol (apreservative). Partly due to these added components, there is currentlya broad-based public concern over the safety of vaccine preparations.Thimerosol, for example, contains mercury and is made from a combinationof ethyl mercuric chloride, thiosalicylic acid, sodium hydroxide andethanol. Furthermore, some studies, although inconclusive, havesuggested a possible link between some vaccine components and potentialcomplications such as those diseases commonly associated withautoimmunity. Thus, more effective vaccine therapies are needed andpublic cooperation with vaccine initiatives will be easier to promote ifthere is a greater degree of comfort with the method of vaccination.

DPMSCs of the present invention can be differentiated to form dendriticcells, which present antigen to T cells and thereby activate them torespond against foreign organisms. These dendritic cells can begenetically altered to express foreign antigens, using techniquespreviously described. A particular advantage of this method of vaccinedelivery lies in the fact that more than one antigen can be presented bya single genetically altered cell.

Differentiated or undifferentiated DPMSC vaccine vectors of heterologousorigin provide the added advantage of stimulating the immune systemthrough foreign cell-surface markers. Vaccine design experiments haveshown that stimulation of the immune response using multiple antigenscan elicit a heightened immune response to certain individual antigenswithin the vaccine preparation.

Immunologically effective antigens have been identified for hepatitis A,hepatitis B, varicella (chickenpox), polio, diphtheria, pertussis,tetanus, Lyme disease, measles, mumps, rubella, Haemophilus influenzaetype B (Hib), BCG, Japanese encephalitis, yellow fever, and rotavirus,for example.

The method for inducing an immune response to an infectious agent in ahuman individual using DPMSCs of the present invention can be performedby expanding a clonal population of dental pulp marrow similar cells inculture, genetically altering the expanded cells to express one or morepre-selected antigenic molecules to elicit a protective immune responseagainst an infectious agent, and introducing into the individual anamount of genetically altered cells effective to induce the immuneresponse. Methods for administering genetically altered cells are knownto those of skill in the art. An amount of genetically altered cellseffective to induce an immune response is an amount of cells whichproduces sufficient expression of the desired antigen to produce ameasurable antibody response, as determined by methods known to those ofskill in the art. Preferably, the antibody response is a protectiveantibody response that can be detected by resistance to disease uponchallenge with the appropriate infectious agent.

DPMSCs and Cancer Therapy

DPMSCs of the present invention provide a novel vehicle for cancertherapies. For example, DPMSCs can be induced to differentiate to formendothelial cells or precursors which will home to endothelial tissueswhen delivered either locally or systemically. The cells participate information of blood vessels to supply newly-formed tumors (angiogenesis),and divide and proliferate in the endothelial tissue accordingly. Bygenetically engineering these cells to undergo apoptosis uponstimulation with an externally-delivered element, the newly-formed bloodvessels can be disrupted and blood flow to the tumor can be eliminated.An example of an externally-delivered element would be the antibiotictetracycline, where the cells have been transfected or transduced with agene which promotes apoptosis, such as Caspase or BAD, under the controlof a tetracycline response element. Tetracycline responsive elementshave been described in the literature (Gossen, M. & Bujard, H., Proc.Natl. Acad. Sci. USA (1992) 89: 5547 5551), provide in vivo transgeneexpression control in endothelial cells (Sarao, R. & Dumont, D.,Transgenic Res. (1998) 7: 421 427), and are commercially available(CLONETECH Laboratories, Palo Alto, Calif.).

Alternately, undifferentiated DPMSCs or DPMSCs differentiated to formtissue-specific cell lineages can be genetically altered to produce aproduct, for export into the extracellular environment, which is toxicto tumor cells or which disrupts angiogenesis (such as pigmentepithelium-derived factor (PEDF), described by Dawson, et al., Science(1999) 285: 245-248). For example, Koivunen, et al., describe cyclicpeptides containing an amino acid sequence which selectively inhibitsMMP-2 and MMP-9 (matrix metalloproteinases associated withtumorigenesis), preventing tumor growth and invasion in animal modelsand specifically targeting angiogenic blood vessels in vivo (Koivunen,E., Nat. Biotech. (1999) 17: 768 774). Where it is desired that cells bedelivered to the tumor site, produce a tumor-inhibitory product, andthen be destroyed, cells can be further genetically altered toincorporate an apoptosis-promoting protein under the control of aninducible promoter.

DPMSCs also provide a vector for delivery of cancer vaccines, since theycan be isolated from the patient, cultured ex vivo, genetically alteredex vivo to express the appropriate antigens, particularly in combinationwith receptors associated with increased immune response to antigen, andreintroduced into the individual to invoke an immune response to theprotein expressed on tumor cells.

EXAMPLES

The examples, which are intended to be purely exemplary of the inventionand should therefore not be considered to limit the invention in anyway, also describe and detail aspects and aspects of the inventiondiscussed above.

Abbreviations: BDNF=brain-derived neurotrophic factors,Beta2/NeuroD=neurogenic differentiation transcription factor (also,beta-cell E-box transactivator 2), bFGF=basic fibroblast growth factor,BHA=butylated hydroxyanisole, BMP-receptor=1B bone morphogenetic proteinreceptor, type IB, c-Met=HGF receptor, DMEM=Dulbecco's modified Eaglemedium, ECM=extracellular matrix, EGF=epidermal growth factor,ES=embryonic stem cells, FACS=fluorescence-activated cell sorting,FBS=fetal bovine serum, FN=fibronectin, GFAP=glial fibrillary acidicprotein, HGF=hepatocyte growth factor, MAPCs=multipotent adultprogenitor cells, NF-M=neurofilament 160-kDa, NF-L=neurofilament 68 kDa,NF—H=200 kDa neurofilament 200 kDa, NGF=β-nerve growth factor,NT-3=neurotrophin-3, NTRK3=NT-3 receptor, Osc=osteocalcin,Osp=osteopontin, Runx2=runt-homology domain transcription factor,SSEA-4=stage-specific embryonic antigen 4, Trk-A=tyrosine kinasereceptor A (also, NGF receptor), TuJ1=β-III-tubulin III.

Example 1A Isolation of DPMSC

Cell Culture

Dental pulp was extracted from normal exfoliated human deciduous teethof 5- to 7-year old children (10 patients) with informed consent of thedonors. Dental pulp was extracted using needle and was transferred into35-mm Petri dishes F12/Medium 199/CMRL 1066 supplemented with 1.25%Human serum and supplemented with 1-50 ng/ml (preferably about 5-15ng/ml) platelet derived growth factor-BB (PDGF-BB), 1-50 ng/ml(preferably about 1-15 ng/ml) epidermal growth factor (EGF), 1-50 ng/ml(preferably about 1-15 ng/ml) insulin-like growth factor (IGF), 1-50ng/ml (preferably about 1-15 ng/ml) fibroblast growth factor-b (FGF-b),10⁻¹⁰ to 10⁻⁸ M dexamethasone or other appropriate steroid, 0-1 μg/mLlinoleic acid, and 10-50 mg/L ascorbic acid. Tissue explant of dentalpulp was used to isolate immature DPMSC. The growing culture of DPMSCwas maintained under these conditions for 1 day and then the cells wereplaced, optionally dissociated, in a collagenase/trypsin/chicken serum(CTC) media, and seeded into 35-mm Petri dishes. The use of CTC mediaaids in the detachment of cells that have developed more cell-to-cellconnection junctions (e.g., tight junctions and desmosomes) and isbetter at detaching cells with such junctions than trypsin alone.

The culture was maintained semi-confluent in order to prevent thedifferentiation of the cells, and the cells were passed every 3 dayswith the medium refreshed two times at week. After 7 days, smallcolonies of adherent cells developed. After 2 weeks, DPMSC cells weresmall highly proliferative cells exhibiting reduced cytoplasm. Growthcurves confirmed that DPMSC proliferated both in mediums with2.5-1.25-0.5% human serum (HS) but that in 0.5% HS, the medium neededreplacing daily, or every two days. The doubling time was estimated in28 hours in 1.25%-2.25% HS medium and 29-30 hours in 0.25%-0.5% HSmedium. DPMSCs showed a normal karyotype.

TABLE 1 Plating Duplication Days Before Medium efficiency TimeStarvation 1-Mid 2.5% HS 135% 28 hours 5 days 2-Mid 1.25% HS 101% 28hours 4 days 3-Mid 0.5% HS  58% 29 hours 3 days 4-Mid 0.25% HS  48% 30hours 2 days

Table 1 shows the index for plating efficiency, duplication time anddays required before medium starvation.

For freezing, the cells were resuspended in a medium containingF12/Medium 199/CMRL 1066 supplemented with 1.25% human serum, growthfactors, and 10% dimethylsulfoxide (Sigma, St. Louis, Mo., USA) at 5×10⁵cells/ml, and the temperature was slowly and gradually decreased at arate of 1° C. per minute until a final temperature of −70° C. wasreached. Thereafter, cells were transferred to liquid nitrogen. Forthawing cryo-vials with DPMSC, the vials were placed into a 37° C. waterbath for 2 minutes and thereafter washed twice with F12/Medium 199/CMRL1066 supplemented with 1.25% human serum, and placed into culture. Allcultures were incubated at 37° C. in a 5% CO₂ and high humidityenvironment.

Despite the high density of the cells exiting the dental pulp, neitherdifferentiation nor slowed proliferation was observed as could beexpected for confluent cell cultures, particularly in the absence ofspecific growth factors. At the same time, both differentiation andslowed proliferation were noted during the subsequent confluent culturefollowing trypsinization. Without being bound by theory, it is possiblethat explanting dental pulp as an outgrowth culture before the initialpassage with trypsinization may prevent any stem cells from undergopremature differentiation.

Example 1B Method of Isolating and/or Culturing DPMSC

Dental pulp was extracted from normal exfoliated human deciduous teethof 5- to 7-year-old children (12 patients) with informed consent of thedonors. Dental pulp was extracted using needle and was transferred into35-mm Petri dishes (Falcon, BD-Biosciences, Italy) with a proliferationmedium composed of F-12 Coon's modified/Ambesi's modified (Gibco)/Medium199 (Sigma Aldrich, Germany)/CMRL 1066 (Sigma Aldrich, Germany)supplemented with 1.25% of Human serum 1-50 ng/ml platelet-derivedgrowth factor-BB (PDGF-BB, Immunotools, Germany), 1-50 ng/ml epidermalgrowth factor (EGF, Immunotools, Germany), 1-50 ng/ml insulin-likegrowth factor-I (IGF-I, Immunotools, Germany), 1-50 ng/ml fibroblastgrowth factor-I (FGF-b, Immunotools, Germany), 10⁻¹⁰ to 10⁻⁸ Mdexamethasone (MP), 20-100 μg/L linoleic acid (Sigma, Germany), 10-50mg/L ascorbic acid (Sigma) and 0.5 ml/L gentamycin (Gibco). The growingculture of DPMSC was maintained under these conditions for 1 day andthen the cells were placed, optionally dissociated, in a mediumcontaining Collagenase II 1000 U/mL (Wortington, USA) plus a CTCsolution (Trypsin 0.5%, Sigma) Collagenase II 22 U/mL (Wortington) andchicken serum 0.2% (Gibco). Cells were then seeded into 35-mm Petridishes.

Dental pulp population of cells was not subjected to any type ofdepletion techniques (e g, immunodepletion or physical or chemicaldepletion) and when colonies developed in primary culture reachedconfluence after 2-3 weeks, cells were detached by CTC and sub-culturedinto 100 mm dishes in the proliferation medium. The culture wasmaintained semiconfluent in order to prevent the differentiation of thecells, and the cells were passed every 3 days at the density of 2·10³cells/cm².

Example 2A Methods of Phenotype Analysis of DPMSC Cell Population

Immunofluorescence, Flow-Cytometry, FISH and Immunoblot

Immunofluorescence and FISH analyses were performed on 4% bufferedparaformaldehyde or methanol/acetone fixed cells, while FACS analysiswas performed on P3-P5 cells detached from the culture substrate througha short incubation in CTC. Staining was performed either using properlyconjugated primary antibodies or with un-conjugated primary antibodiesfollowed by an incubation with conjugated secondary antibodies.Intracellular staining was performed after a permeabilization steputilizing the Intrastain Fixation and Permeabilization kit (Dako,Danmark), following the manufacturer's instructions.

Image acquisition was carried out by a Confocal Laser Microscope (LeicaTCS-SP2, Leica Microsystems, Italy), utilizing either a 63× oilimmersion objective (numerical aperture: 1.40) or a 40× oil immersionobjective (numerical aperture: 1.25). Epifluorescence and phase contrastimages were obtained utilizing a live cell imaging dedicated systemconsisting of a Leica DMI 6000B microscope which is connected to a LeicaDFC350FX camera (Leica Microsystems, Italy). A 10× objective (numericalaperture: 0.25) was employed for this purpose. Bright field images werecaptured utilizing an Olympus AX70 microscope connected to an OlympusDP50 camera (Olympus, Italy). A 10× objective (numerical aperture: 0.40)was employed for this purpose. Adobe Photoshop software was utilized tocompose, overlay the images and to adjust contrast (Adobe, USA).

FISH (Fluorescence-in-situ-hybridization) was performed utilizing X- andY-chromosome probes (Vysis), following the manufacturer's instructions.DNA content of ethanol-fixed and propidium iodide-stained cells wasdetermined.

Lysates for immunoblot were collected using the TRIzol Reagent (Gibco,Italy) as recommended by the manufacturer, and then quantified by BCAProtein Assay Reagent Kit (Pierce) and program LABSYSTEMS GENESIS V2.16.Samples were electrophoresed on a SDS-PAGE gel and transferred to apolyvinylidene difluoride membrane or nitrocellulose transfer membrane(Protran nitrocellulose transfer membrane; Schleicher & Schuell).Membranes were blocked in Tris-buffered saline with 5% BSA and 0.5-1%Tween. Antibody/antigen complexes were detected using ECL reagent(Amersham Biosciences)

RT-PCR Analysis.

Total RNA was extracted from 2.5×10⁶ DPMSC cells grown in expansion ordifferentiation media, using TRIzol Reagent (Gibco, Italy), asrecommended by the manufacturer. After treatment with DNase I (Ambion,USA), first strand cDNA synthesis was performed with 2 μg total RNAusing random hexanucleotides and M-MLV reverse transcriptase(Invitrogen). PCR amplification was carried out in a final volume of 50μl, using an amount of cDNA ranging from 80 ng to 150 ng, 10 mM Tris-HClpH 9.0, 1.5 mM MgCl₂, 0.2 mM dNTPs, 25 μmol of each primer and 2U Taq Ipolymerase (Amersham, Italy). The PCR conditions are described in Table2

The optimal conditions and the number of cycles were determined to allowamplification of samples within the linear phase of the PCR. Thereaction products were analyzed on 1-2% agarose gels.

TRAP-Assay.

The detection of telomerase activity was performed utilizing the TRAPezekit (Chemicon International) following the manufacturer's instructions.

Karyotyping.

Metaphase spreads were prepared from single-cell derived clones,cultured in the proliferation medium for 72 hours. Chromosome analysiswas performed according to the standard procedures using QFQ and RBAbanding techniques at 400-650 band resolution, respectively.

Von Kossa Staining.

Cells, fixed in 4% paraformaldehyde for 20 minutes, were treated with 2%silver nitrate (Sigma) in a clear glass coplin jar placed directly infront of a 60-W lamp for 1 hour. Slides were rinsed in distilled water(dH₂O), fixed with 2.5% sodium thiosulphate (Sigma) for 5 minutes, andwashed in dH₂O. Cells were counterstained with Nuclear Fast Red (Sigma)for 1 minute and rinsed in tap water.

Alkaline Phosphatase Staining.

Cells differentiated for 28 days in ostogenic medium were fixed at −20°C. in methanol for 2 minutes and washed in 100 mM Tris-HCl, pH 9.5, 100mM NaCl, and 10 mM MgCl₂ buffer (Sigma) for 10 minutes. Slides were thenstained with fast 5-bromo-4-chloro-3-indolyl phosphate and nitrobluetetrazolium alkaline phosphatase substrate (Sigma) for 5 to 10 minutesand rinsed in dH₂O.

Periodic Acid-Schiff Staining for Glycogen Detection.

Slides were oxidized in 1% periodic acid for 5 minutes and rinsed threetimes in dH2O, Slides were then treated with Schiff's reagent for 15minutes, rinsed in dH2O for 5-10 minutes, stained with Mayer'shematoxylin for 1 minute, and rinsed in dH2O.

Albumin and Urea Production

After differentiation for 17 days, medium was removed. Before addingfresh medium, cells were washed with HBSS. After 4 days, supernatantswere collected and immediately snap-frozen. Albumin concentrations weredetermined by ELISA assays (Human Albumin Elisa Quantitation KitBethyl—Montgomery, Tex.), following the manufacturer's instructions.Urea concentrations were determined by QuantiChrom™ Urea Assay Kit(BioAssay Systems Hayward) following the manufacturer's instructions.

Example 2B Phenotype Analysis of DPMSC Cell Population

RT-PCR revealed expression of Oct-4 Isoforms A-B, Sox-2, Nanog, Klf-4,c-Myc and Rex-1. DPMSC expressed mRNA for Rex-1 (low), Klf-4, Oct-4 isoA-isoB, Sox-2, Nanog, and c-Myc. It should be noted that over-expressionof Klf-4, Oct-4 iso A-isoB, Sox-2, and c-Myc in somatic cells can permittheir return to an undifferentiated stem stage.

Expression mRNA of sternness transcription factors in DPMSC was comparedwith NTERA2 embryonic stem cell line. Staining with antibodies confirmedthat about 99% of the cells were strongly positive for Oct-4, Sox-2 andNanog. The uniformity of expression of Oct-4 and Nanog was furtherconfirmed by flow cytometry, while as expected, human primaryfibroblasts were negative for this marker.

99% of OCT-4 expression was observed for DPMSC cells in proliferationand the signal had both cytoplasmic and nuclear localization. Immunoblotshowed the presence of two isoforms of Oct-4 with the same grade ofexpression of control+cells NTERA-2 Immunofluorescence analysis showedthat about 96% of the DPMSC cell population expressed Oct-4. FACSanalysis also showed that about 99% of the cell population expressedSox-2 expression for DPMSC cells in proliferation and that the signalhad both cytoplasmic and nuclear localization. About 99% of the DPMSCcells in proliferation expressed Nanog and the signal was exclusivelynuclear localization.

It should be noted in this respect that only a small fraction ofamniotic stem cells was shown to be positive for Oct-4, while thepercentage of Oct-4-positive cells varied from <0.01 to 80%, dependingon the O₂ concentration in m-MAPC (Jiang et al., 2002). The highpercentage of positive cells for Oct-4, Sox-2, and Nanog indicated anextremely uniform population of stem cells. Consistent with thisobservation, as shown below, we noted uniform differentiation of theentire stem cell population toward the same tissue type. Other ESmarkers, SSEA-3, SSEA-4, and TRA-1-60, TRA-1-81 and ALP were lessuniformly expressed in DPMSC cells, but not SSEA-1.

Experiments were conducted to determine that ALP mRNA expression inDPMSCs was comparable to NTERA2 cells. In an alkaline phosphatase assayand BICP/NBT substrate transformation, DPMSCs demonstrated a highenzymatic activity in proliferation phase. DPMSCs showed no detectablesignal for SSEA-1 and a low but present signal for SSEA-3 in 99% ofcells. DPMSCs were 92% positive in a FACS analysis for SSEA-4 and SSEA-4antibody stains DPMSC as well. Immunofluorescence studies for TRA-1-60resulted in a low but integral positive signal for DPMSCs.Immunofluorescence studies for TRA-1-81 resulted in a low but integralpositive signal for DPMSCs.

Additionally, the outgrowth cells were uniformly positive for humanmesenchymal stem cell-specific antigens by FACS and expressed highlevels (>90-95%) of CD10, CD29, CD13, CD44, CD49a, CD49d, CD59, CD73,CDw90, CD105, and Oct-4.

The outgrowth cells expressed low levels of CD66e, KDR, CD133, VE-Cad,and CD117. The phenotype was more homogenous and the same results wereobtained after thawing, but their protein level decreased in human DPMSCcultures beyond 40 cell doublings, which may have been due to a partialloss of undifferentiated phenotype. A very small percentage (e.g., <1%)of the DPMSCs did expressed CD34 and CD45. The expression level of thefollowing markers in the DPMSC cell population was as follows:

Percentage Expressed in Marker DPMSC cell population CD-10 92.58% CD-13  100% CD-29   100% CD-44    99% CD-49a    99% CD-49d   100% CD59   100%CD-73   100% CD-90   100% CD-105    99% CD-66e  0.79% KDR  4.47% CD-133 2.28% VE-Cad  1.61% CD-117 17.52% CD-34   0.2% CD-45  0.44%

RT-PCR analysis of mRNA expression of the stem cell marker hTERT inDPMSC cell isolates was also conducted and relative telomerase activitycompared with NTERA2 and KitCtr+positive controls. The telomere lengthof DPMSC P2 and P5 from a donor, age 6, was determined using Flow Fishtechniques. Telomere length was (18.4%) about 14.7 Kbp P2 and (17.16%)about 13.8 kbp P5, respectively, 1301 cells (long telomeres). We haveproved telomerase mRNA presence by rt-PCR, and its enzymatic activitythat was 15.8% with respect to NTERA2 cells.

The presence of Oct-4, Sox-2, and Nanog combined with SSEA-4, SSEA-3,TRA-1-60, TRA-1-81, ALP, TRT presence and activity and telomere lengthare markers that correlated with presence of the most primitive cells inDPMSC cultures, like the absence of SSEA-1. During the proliferationphase, immunofluorescence was conducted to determine protein expressionof Collagen I, Fibroblast Growth Factor receptor-1 (FGFr-I), GrowthFactor receptor-II (FGFr-II), cardiac Troponin T (c-TnT), Smooth MuscleActin (SMA), Neurofilament light (NF-L), Glial Fibrillar acidic protein(G-Fap), Neural Specific Enolase (NSE), Core Binding Factor Type I andII (Cbfa-I Ty I, II), Muscle segmental Omeobox 2 (Msx-2), Neuro-D,Connexin-43, Abcg-2, Serca-2a, Nestin, Vimentin. Messenger expressionduring proliferation phase was determined by RT-PCR and showed theexpression of MDR-1, Abcg-2, FGFr-I, FGFr-II, Msx-2, Dlx-5, PPAR-γ,c-Met, CK-19, Alkaline phosphatase, Osteocalcin, Osteonectin, BMP-2,BMP-4, BMP-7, BMPr-Ia, BMPr-Ib, Cbfa-I type I, Cbfa-I type II, CollagenType I, Aggrecan, Dermo-I, Dental matrix protein, G-Fap, Glypican,β³-Tubulin, Neurofilament light, medium and heavy, NSE, Musashi,Vimentin, Sarcomeric actin (ASA), SMA, Cardiac actin, Myocardin, ANP,Gata-4, Nkx-2.5, Myosin heavy chain Immunoblot analysis showed theexpression of ASA, Serca 2a, β³-Tubulin, Msx-2, Connexin-43, Dlx-5,Neuro-D, Ca-Channel DHPR, Cbfa-I Ty I-II.

FGFr-II was expressed at low degree during proliferation and at times,absent. In proliferation phase, 99% expression of Connexin-43 wasobserved. Cx-43 expression was observed by immunoblot both inproliferation and myocyte differentiation. GATA-4 expression showednuclear and cytoplasmic (perinuclear) staining. Abcg-2 mRNA wasexpressed at high levels both in proliferation and hepaticdifferentiation. MDR-I and Abcg-2 mRNAs were expressed both inproliferation and differentiation. Immunohistochemistry and fluorescenceexperiments for neuro D expression on DPMSC during proliferation phaseshowed nuclear localization. Immunoblot in proliferation and neuronaldifferentiation showed no expression only after completedifferentiation. Smooth muscle actin, protein and mRNA were expressedduring proliferation phase. Cardiac specific actin isoform showed lowexpression, protein and mRNA presence in proliferation. Nestin, a neuralstem cell marker, protein was expressed in DPMSC. Vimentin, anotherneural stem cell marker, protein and mRNA were expressed in DPMSC duringproliferation phase.

A population of identical cells from non-deciduous, permanent adultteeth were obtained and analyzed for immunophenotype as shown:

Surface Antigens Commercial Medium Mid 1.25% HS CD-13  45.58% 99.99%CD-29  87.50% 99.18% CD-34   0.07%  0.04% CD-45   0.27%  0.08% CD-49a87.47% 95.73% CD-73  99.87%   100% CD-90  97.51%  99.9% CD-105    55%96.89% CD-117  0.70%  2.01% CD-133  0.50%  0.64% KDR  0.51%  1.47%VE-Cad  0.03%  1.61% CD-59  99.90% 99.99% CD-49d 63.44% 99.84% CD-44 76.84% 99.67% CD-10  15.55% 94.00% CD-66e  0.37%  0.88%

Immunophenotypic analysis by FACS of human adult third molar DPMSC 3°obtained after 14-20 cell doublings showed that a low percentage (e.g.,<1%) of the cells did not express CD34, CD45; and that a high percentage(e.g., >90%) of the cells in the population expressed CD10, CD29, CD13,CD44, CD49a, CD49d, CD59, CD73, CDw90, and CD105. The population ofcells expressed low levels of CD66e, KDR, CD133, VE-Cad, and CD117. Thephenotype of the population of cells obtained using the protocols andmedium described herein was highly homogenous as compared to thephenotype which was obtained using a simple commercial medium.

Without being bound by theory, it is possible that DPMSC represent asubpopulation of Dental Pulp that under our experimental conditions werepredominantly and selectively proliferating. The gradient between thepiece of dental pulp and the culture medium may serve as a vectordirecting the cells toward what they perceive as a site of injury, whichleads to their continued and selective migration in the Petri dish.

Growth curves confirmed that DPMSC proliferate at high rate in mediumswith 1.25-2.5% and even with 0.25-0.5% Human serum (HS), but in thelatter conditions they need daily, or every two days, medium replacing;doubling time was estimated in 28 hours in 1.25-2.5% HS medium and 29-30hours in 0.25-0.5% HS medium. Such high proliferation grade, as comparedto BMSC, agrees with results obtained from Ghronthos S. Et al 2000 andPierdomenico L. et al 2005.

It should be noted in this respect that over-expression of Klf-4, Oct-4iso A-isoB, Sox-2, c-Myc in somatic cells may permit their to return inindifferentiate stem stage (Wernig M. et al 2007, Meissner A. et al2007).

DPMSC, like MIAMI cells, express a high number of different types ofmessenger RNA found during all three germ layers terminal tissuespecific differentiation. The question of why such high degree ofextranuclear signals for many nuclear factors, such as Sox-2, Gata-4,Cbfa-I, Neuro-D/Beta2, HNF-3β, HNF4α, Msx-2, Dlx-5 and others werepresent was investigated. Without being bound by theory, it is possiblethat this atypical pattern of expression is the result of anaccumulation of inactivated nuclear factors that permits to the cells arapid response to a differentiation stimulus. This hypothesis couldexplain the expression of the numerous m-RNA species, normallyassociated to differentiation, in undifferentiated cells, suggestingthat they could be molecularly equipped to remain pluripotent or toprogress to diverse lineages. The likeness in population purity betweenIDPSC (Kerkis et al 2006) and the population of cells described in thepresent study leads us to believe that they are similar. The differenceconsists in the use of a medium with very low human serum which makesour cells more suited for human clinical applications.

DPMSC cells, and the medium used for their selection, hold strongpromise in clinical reparative medicine for the treatment ofdegenerative or inherited diseases and are free of the ethical concernsraised by the use of ES cells. Autologous ex vivo expanded DPMSC cellscould be used for autologous implantation aimed to repair damaged, agedor diseased tissues and organs. The ability to stably transduce DPMSCcells with specific genes, would also enable the genetic manipulation ofautologous cells for the treatment of degenerative and congenitaldisorders.

Example 3A Inducing DPMSCs to Differentiate to Form CommittedProgenitors and Tissue-Specific Cell Types

Using appropriate growth factors, chemokines, and cytokines, DPMSC ofthe present invention were induced to differentiate to form a number ofcell lineages, including a variety of cells of mesodermal origin as wellas cell from neuroectodermal origin and endodermal origin.

Osteoblastic Differentiation

About 20,000 DPMSCs/cm² were cultured in F-12 medium with aboutDexamethasone (from about 10 nM to about 500 nM), β-glycerophosphate(from about 1 mM to about 5 mM), ascorbic acid (from about 10 mg/ml toabout 100 mg/ml), Ca²⁺ (from about 1 mM to about 2 mM), Mg²⁺ (from about0.1 mM to about 1 mM), glucose (from about 1 g/ml to about 5 g/ml),human serum (from about 0.5% to about 2%), retinoic acid (from about 100nM to about 500 mM), 17-β-Estrogen (from about 0.1 μM to about 10 μM),Vitamin K2 (from about 0.1 μM to about 10 μM), Vitamin D3 (from about0.1 nM to about 10 nM) and Calcitonin (from about 0.1 nM to about 10nM). To demonstrate presence of osteoblasts, we used Von Kossa stainingassay (silver reduction of CaPo4) for mineral deposition and antibodiesand primers for detecting osteonectin, connexin-43, osteopontin (earlyosteoblastic marker) and osteocalcin (late osteoblastic marker) afterabout 3 months of culture. At the same time, we had analyzed thepresence, by rt-PCR, for BMPr-1a, 1b, BMP-2, and BMP-4. We also usedx-Ray diffraction patterns to evaluate the presence of hydroxyappatiteformation.

In one method, DPMSC cells were suspended in an osteoblastic medium andplaced in a Petri dish, such as a culture dish. DPMSC cells were allowedto settle to the bottom of the culture dish. Osteoblasticdifferentiation may be expected to occur, for example, in a 100%humidified atmosphere of 95% air, 5% CO² at 37° C. Osteoblasticdifferentiation was detected after about 2 weeks to about 8 weeks andranged from about 3 weeks to about 4 months.

Changes in morphology were observed after 3 months of osteoblasticinduction. Core binding factor Type I and II were detected by rt-PCR inDPMSC cells in proliferation and osteoblastic differentiation.Immunoblot showed Cbfa-I, osteoblastic master gene, isoforms expressionin DPMSC cells. Cbfa-I was expressed in proliferation and after 3months, osteoblastic differentiation. Msx-2 was constitutively expressedboth in proliferation and differentiation population. Dlx-5 wasdown-regulated in differentiation as shown both by rt-PCR andimmunoblot. mRNA expression of extracellular matrix proteins: collagenI, alkaline phosphatase, osteocalcin, and osteonectin in theproliferation and differentiation population.

rt-PCR analysis was conducted for detection of early osteoblastic markerosteopontin in proliferation and after 14 days and 3 months ofosteoblastic induction. Very little to no osteopontin expression wasobserved during proliferation while an increased expression was observedat 14 days and a decreased expression was observed after 3 months ofdifferentiation. In the differentiation stage, connexin-43 andosteopontin were co-expressed Immunofluorescence showed the absence ofosteocalcin during proliferation whereas osteocalcin was expressed afterosteoblastic differentiation.

Example 3B Osteoblastic Differentiation

About 40,000 DPMSC cells/cm² were cultured in F-12 Coon'smodified/Ambesi's modified medium with Dexamethasone (from about 100 nMto about 25 nM, MP, Biomedicals), (3-glycerophosphate 1.5 mM (Sigma),ascorbic acid-3P 13.5 μM (Fluka), Ca²⁺ 1.2 mM (Sigma), Mg²⁺ 0.6 mM(Sigma), Glucose 2 g/L (Sigma), human serum from 0.5% to 1%, RetinoicAc. 250 nM (MP), 17-β-Estrogen 1 μM (MP, Biomedicals), Vitamin K2 10 μM(Sigma), Vit. D3 (from about 5 nM to about 10 nM, Sigma) and Calcitonin(from about 1 nM to about 2 nM, MP, Biomedicals).

In one aspect of the invention, DPMSC cells were suspended in anosteoblastic medium and placed in a culture dish. In this example, DPMSCcells were allowed to settle to the bottom of the culture dish to form a3D structure. Osteoblastic differentiation may be expected to occur, forexample, in a 100% humidified atmosphere of 95% air, 5% CO₂ at 37° C.Osteoblastic differentiation may be detected between 2 weeks to 8 weeks.

To confirm osteogenesis, cells were examined by RT-PCR for theexpression of several genes, including osteocalcin (OSC), Collagen I,CBFA-1, ALP, osteonectin (OSN), osteopontin (OP), bone morphogenicprotein-2,4,7 (BMP-2, -4, -7), in addition to receptors involved inosteogenesis bone morphogenic protein receptor-Ia, Ib-II (BMPr-Ia, -Ib,II) and the homeodomain proteins muscle segmental omeobox-2 (Msx2) anddistal-less 5 (Dlx5).

Expression of CBFA-1 type I and II, a transcription factor that binds tothe promoters of several osteogenic genes (Ducy et al., 1997), wasobserved at all time points in osteo-induced DPMSC cells. CBFA-1 type Iexpression was not specific to osteo-induced cells as a basal expressionwas observed in non-induced DPMSC cells. Quantification of CBFA-1 type Iand II expression by semiquantitative PCR, confirmed a time-dependentincrease in gene expression compared with non-induced DPMSC for type IIand a decreased time-dependent expression compared with non-inducedDPMSC for type I. These data were supported by western blot that alsoevidenced CBFA-1 proteins expression.

ALP and Collagen I expression were observed at all time points indifferentiated and control DPMSC cells, however, continued treatment for90 days resulted in an increase in ALP and Collagen I expression levels.In addition to CBFA-1, Collagen I and ALP, OSN expression was alsoobserved in differentiated and control DPMSC cells. Although theexpression of these genes is indicative of osteogenesis, they are notspecific markers. However, expression of the late differentiationbone-specific gene OSC was observed in both induced and non-inducedDPMSC cells. OSC protein was only expressed after 3 months of induction,as determined by immunofluorescence and immunoblot. It has also beendemonstrated in the literature (Nefussi J. R. et al 1997).

The early osteoblastic differentiation marker (Yamamoto N. et al 2002)OSP expression in osteo-induced DPMSC cells seemed to be triphasic: notexpressed during proliferation, highly expressed at 14 days anddecreased expression after 3 months of induction. These data wereconfirmed by immunofluorescence. Both osteo- and non-induced DPMSC cellsexpressed homeodomain protein msx-2, a gene involved in osteoblastdifferentiation (Benson et al., 2000). D1x5 was detected in non-inducedDPMSC cells and its expression decreased in induced DPMSC cells. Datawere confirmed by Western Blot.

BMP-2 and 4 expression was observed at all time points in differentiatedand control DPMSC cells. At the same time, the expression of BMPr-Ia andIb was observed at all time points, but with an increased expressionlevel in the differentiated cells. On the other hand, the expression ofBMP-7 messenger was present only during proliferation and BMPr-IIexpression was always absent on DPMSC cells.

During differentiation, some mineral nodules appeared and Von Kossastaining assay (silver reduction of CaPo4) was used for revealingmineral deposition. X-Ray diffraction patterns were also used toevaluate the presence of Hydroxyapatite formation. 3D-Aggregateexperiments showed the same results Immunostaining was demonstrated tobe specific in experiments where no staining was detected when primaryantibodies were used as a negative control and Hobit cell line (KeetingP. E. et al 1992) was used as a positive control.

Example 4A Generation of Neural Cells from Adult Dental Pulp Stem Cells

Differentiated neurons are post-mitotic, thus, little or no neuronalregeneration is usually observed in vivo. Therapies forneurodegenerative and traumatic disorders of the brain may besignificantly furthered if new, proliferating neural stem cells (NSC)could be introduced in the defective areas of the brain which wouldresume the function of the defective tissue. DPMSCs selected frompost-natal bone marrow that differentiate to all mesodermal cell typescan also differentiate to neurons, oligodendrocytes, and astrocytes.

DPMSC cultures were established as described above. Neural developmentwas induced as follows: Generations of neurons, astrocytes andoligodendrocytes were grown in medium consisting of neuraldifferentiation medium. This medium comprised the following: DMEM-HG,1×ITS, and 0.5-100 ng/mL FGF (preferably about 10 ng/mL). The mediumalso contained one or more of the following cytokines in order to inducedifferentiation into certain cell types: 5-50 ng/mL BDNF (preferablyabout 16 ng/mL) for dopaminergic neurons. The choice of growth factorsto induce differentiation of DPMSCs into neural cells was based on whatwas known in embryonic development of the nervous system or from studiesthat evaluated in vitro NSC differentiation. Astrocytes were identifiedas glial-fibrilar-acidic-protein (GFAP) positive cells, oligodendrocyteswere identified as glucocerebroside positive (GalC) and neurons wereidentified as cells that express in a sequential fashion NeuroD,Tubulin-MB (Tuji), synaptophysin and neurofilament-68, 160-200 kDa.

Other growth factors that are specifically expressed in the brain andthat affect neural development in vivo and in vitro include brainderived neurotrophic factor (BDNF), glial derived neurotrophic factor(GDNF) and ciliary neurotrophic factor (CNTF). BDNF is a member of thenerve growth factor family that promotes in vitro differentiation ofNSC, human subependymal cells, and neuronal precursors to neurons andpromotes neurite outgrowth of hippocamal stem cells in vivo. Consistentwith the known function of BDNF to support survival of dopaminergicneurons of the substantia nigra, when DPMSCs were treated with 16 ng/mLBDNF and 10 ng/ml EGFR, exclusive differentiation into tyrosinehydroxylase positive neurons was observed.

The ease with which DPMSCs was isolated from post-dental pulp, ex vivoexpanded and induced to differentiate in vitro to glial cells orspecific neuronal cell types circumvented one of the key problems in NSCtransplantation, namely the availability of suitable donor tissue.

Generally, neural differentiation proceeds in at least three sequentialsteps: neural specification, neural commitment, and neuraldifferentiation. Neural specification was induced by contacting 3000DPMSC/cm² cells with a neural specification medium. A neuralspecification medium included a minimum essential medium, such asDMEM-HG. A neural specification medium typically contained one or moreadditional additives, such as serum, antibiotics, growth factors,nutrients, or combinations thereof.

Specific non-limiting examples of such additives include serum (fromabout 5% to about 25% by volume).

DPMSC cells were incubated in a neural specification medium forsufficient time to induce neural specification. Such incubation time wasbetween about 12 hours to about 36 hours, such as about 24 hours or 1-2days. Neural commitment was induced by contacting neurally specifiedDPMSCs with a neural commitment medium. A neural commitment mediumincluded a minimum essential medium, such as DMEM-HG. A neuralcommitment medium typically contained one or more additional additives,such as antibiotics, growth factors, nutrients, or combinations thereof.Examples of such additives included: EGF (from about 1 ng/ml to about100 ng/ml) NT-3 (from about 1 ng/ml to about 100 ng/ml), NGF (from about1 ng/ml to about 100 ng/ml), and BDNF (from about 5 ng/ml to about 500ng/ml). BHA (from about 0.1 μM to about 100 μM) IBMX (from about 0.1 μMto about 100 μM) ATRA (from about 0.1 μM to about 10 μM) Progesteron(from about 0.1 nM to about 100 nM) 20 nM. Neurally specified DPMSCswere incubated in a neural commitment medium for sufficient time toinduce neural commitment. Such incubation time was between about 10 daysto about 20 days, such as about 15 days.

The number of neurites per neuron increased from 3 to 4 weeks afterdifferentiation. Differentiation to cells with characteristics ofneurons was confirmed by demonstrating presence of GFAP,neurofilament-160, synaptophysin, β³-Tubulin by Western blot. Thepresence of synaptophysin, Synapsyn I, Neurofilament 160, β³-Tubulin,N-caderin, Tyrosine hydroxylase, Neuro-D, N-Cadherin, Neurofilament-68,NSE, Nestin, p75-NGFr and Vimentin was detected by immunofluorescence.Expression of β³-Tubulin, Neurofilament-68, -160, -200, vimentin, NSE,β³-Tubulin, G-Fap, Glypican, Musashi, and nestin was detected by rt-PCR.

Example 4 B Neurogenic Differentiation

Neural specification is induced by incubating DPMSC cells (3,000cells/cm²) in DMEM-high glucose (Invitrogen) with 10% FBS. After 24hours, medium was replaced with neural commitment medium with DMEM-highglucose, 10% FBS containing B27 (Invitrogen), 10 ng/ml EGF (PeprotechEC) and 20 ng/ml bFGF (Peprotech EC) for 15 days. Cells were then passed1:3 and placed in neural commitment medium with NT-3 20 ng/ml(Immunotools), NGF 20 ng/ml (Immunotools), BDNF 50 ng/ml (Immunotools),BHA 20 μM (Sigma), IBMX 50 μM (Sigma), ATRA 1 μM (Sigma), andProgesteron 20 nM (Sigma).

Neural differentiation is induced by contacting neurally committed cellswith a neural differentiation medium, that consists of DMEM, NT-3 20ng/ml (Immunotools), NGF 20 ng/ml (Immunotools), BDNF 50 ng/ml(Immunotools), 5 μg/ml insulin (Sigma), 200 μM and indomethacin (Sigma)and 0.5 mM IBMX (Sigma). Neurally committed DPMSC cells were incubatedin a neural differentiation medium for 1 day.

In one aspect of the invention, DPMSC cell pellets were suspended inthree sequential mediums in a culture dish. In this example, DPMSC cellswere allowed to settle to the bottom of the culture dish to form a3-dimensional (3D) structure. Neural differentiation may be expected tooccur, for example, in a 100% humidified atmosphere of 95% air, 5% CO₂at 37°. Neural differentiation may be detected in 4 weeks.

The morphology of the neural-induced DPMSC cells closely resembled thatof mature neurons: they had a large number of neurites, increased from 3to 4 weeks after differentiation, and with significant branching.

Semiquantitative rt-PCR showed that DPMSC cells expressed β³-Tubulin,Neurofilament-68, -160, -200, vimentin, NSE, G-Fap, Musashi, both at lowlevels in proliferation and at high levels after induction. Neural stemprecursor marker, Vimentin, was expressed both in proliferation andneural differentiation, but during the induction, it was less organized.Neuro-endocrine nuclear factor, Neuro-D/Beta-2, was expressed onlyduring proliferation as demonstrated by both immunofluorescence andWestern blot.

Expression of Nestin, another neurofilament neural stem marker, wasdecreased from the proliferation to induction stage. β³-Tubulin waslargely expressed in 99% of DPMSC cells after differentiation assayed byboth immunofluorescence and Western blot. Structural neurofilamentsNF-160 and NF-200 were expressed only during differentiation, thepositivity was about 50% for the first and a lesser extent for thesecond, which is consistent with a mature neural phenotype (D'ippolitoG. et al 2004). Data were also confirmed by immunoblot for NF-160. Incontrast, NF-68 protein was always expressed during proliferation andafter neural induction, as shown for NSE.

Synaptic vescicle traffiking markers Synapsyn-I and synaptophysin wereexpressed only after differentiation in all neural induced DPMSC cells,at the same time, Tyrosine hydroxylase, N-caderin, and p75-NGFr weredetected using immunofluorescence only after induction.

The Oligodendrocyte marker-4 (O-4) was not expressed. G-Fap, astrocytemarker, was expressed during both proliferation and neuraldifferentiation, but was less organized during the induction. GFAP andbeta3-tubulin were co-expressed, consistent with recent findings (SoenY. et al 2006). 3D-Aggregate experiments showed the same results.Specific immunostaining was demonstrated in experiments where nostaining was detected when primary antibodies were used as negativecontrols and Be2C glioblastoma cell line was used as positive control.

Example 5A Cardiomyocyte Differentiation

Differentiation to any cardiomyocytes can be achieved by plating DPMSCat 10,000 cells/cm² prior to induction of differentiation. To inducecardiomyocyte cell differentiation, confluent DPMSC cells were treatedwith DMEM HG with FBS (from about 1% to about 10%), IBMX (from about 0.1mM to about 10 mM), VEGF (from about 1 ng/ml to about 20 ng/ml). DPMSCcells were suspended in a cardiomyocyte medium and placed in a culturedish. DPMSC cells were allowed to settle to the bottom of the culturedish. Cardiomyocyte differentiation was expected to occur, for example,in a 100% humidified atmosphere of 95% air, 5% CO2 at 37°. Cardiomyocytedifferentiation was detected between about 2 weeks to about 3 months.Muscle differentiation in vitro was demonstrated by detecting sequentialactivation of actinin, skeletal and cardiac actin and skeletal myosin,either by immunohistochemistry or Western blot and rt-PCR analysis usingcommercially available antibodies and specific primers. Byimmunohistochemistry, 90% of cells expressed mature muscle proteinsafter 14 days. Treatment with differentiation medium resulted inexpression of ASA, Ca-channel DHPR, SMA, c-TnT, Connexin-43, Msx-2,Myosin heavy chain, Gata-4, Serca 2A during the 18 days of culture. Inaddition, cardiac heavy myosin were organized and co-expressed with ASAup to 30 days, like Actinin.

Example 5B Cardiomyocyte Differentiation

Differentiation to any muscle phenotype required that DPMSC were platedat 11,000 cells/cm² prior to induction of differentiation. To inducecardiomyocyte cell differentiation, confluent DPMSC cells were treatedwith DMEM with 5% FCS (Sigma-Aldrich), 10 ng/mL bFGF, 10 ng/mL VEGF, and10 ng/mL IGF-1 (all from Peprotech EC). Cells were allowed to becomeconfluent and cultured for about 2 weeks to about 3 months with mediumexchanges every 4 days.

In one aspect of the invention, DPMSC cells were suspended in acardiomyocyte medium and placed in a culture dish. In this example,DPMSC pellet cells were allowed to settle to the bottom of the culturedish to form a 3D structure. Cardiomyocyte differentiation may beexpected to occur, for example, in a 100% humidified atmosphere of 95%air, 5% CO₂ at 37°. Cardiomyocyte differentiation may be detectedbetween 2 weeks to 3 months. Cardiomyocyte differentiation may bedetected between about 2 weeks to about 3 months. During thisdifferentiation period, cells became long and irregular. Co-expressionof Atrial natriuretic peptide (ANP), Smooth muscle actin (SMA), Skeletalmuscle actin (SKMA), Cardiac actin (CA), cardiac-Troponin T (c-TNT),Miocyte enancer factor-2a (MEF-2a), and Myosin heavy chain (Mhc) wasdetected by semiquantitative rt-PCR during both proliferation anddifferentiation. The expression was increased in the last phase.

Messanger expression for Gata-4 and Nkx-2.5 was very low in both phases.Msx-2 m-RNA expression was very high in proliferation anddifferentiation. Expression of Myocardin was decreased afterdifferentiation. It was shown that cells had organized filaments ofα-actinin, α-sarcomeric actin and Myosin heavy chain. Data was confirmedby Western blot. α-sarcomeric actin and Myosin heavy chain wereco-expressed and organized in a fraction of differentiating cells,consistent with the literature.

Gap junctions were demonstrated by the presence of connexin-43 inproximity to cell to-cell contact sites. L-Type calcium channels,Serca-2 ATPase pump, c-TNT were also identified in differentiated cells.SMA was expressed at high degree during the proliferation stage and itsexpression was decreased after induction, without losing the filamentousstructure as shown by immunofluorescence.

It has been reported that α-smooth muscle actin (SMA) is present inembryonic and fetal but not in adult cardiomyocytes, suggesting thatthese cardiomyocytes may represent an early stage of cardiomyocytes(Leor J. et al 1996, Etzion S. et al 2001). Expression of Msx-2 wasdecreased constantly from proliferation to differentiation stage,whereas GATA-4 expression was lost after cardiomyocyte induction.3D-Aggregate experiments showed the same results. Specificimmunostaining was demonstrated in experiments where no staining wasdetected when secondary antibodies were used as negative controls andexplanted cultured pieces of heart were used as positive controls.

Example 6A Hepatic Differentiation

To obtain hepatic cells, DPMSC were plated at 20,000 cells/cm² prior toinduction of differentiation with DMEM low glucose 1-10% FCS, hepatocytegrowth factor (HGF) (from about 1 ng/ml to about 100 ng/ml), oncostatin(OSM) (from about 1 ng/ml to about 100 ng/ml), nicotinamide (from about1 mM to about 100 mM), LDL (from about 0.1 μg/ml to about 10 ng/ml),FGF-4 (from about 1 ng/ml to about 100 ng/ml), insulin (from about 1μg/ml to about 10 μg/ml), linoleic acid (from about 180 μg/L to about 1mg/L), and glucose (from about 1 g/L to about 10 g/L). After 14-37 days,small epithelioid cells were seen that expressed and secreted albumin.In addition, the cells expressed mRNA for HGF receptor, cytokeratin 19,Abcg-2, MDR-I, transferrin, somatostatin, erythropoietin, cytochromeP-450 subunit 2e 1. The presence and secretion of albumin, urea,cytokeratin-8-18-19, HNF-3β and HNF-4-α suggested possibledifferentiation to hepatic cells.

Example 6B Hepatic Differentiation

Hepatocyte differentiation was induced in confluent DPMSC cells byincubating with DMEM low glucose 1% FCS, hepatocyte growth factor 20ng/mL (HGF) (Immunotools), Oncostatin 10 ng/ml (OSM) (Sigma),Nicotinammide 10 mM (Sigma), LDL 1.25 μg/mL (Sigma), FGF-4 10 ng/mL(Sigma), Insulin (from 1 μg/ml to 10 μg/ml) (Sigma), Linoleic acid0.00018 g/L (MP) and glucose 1.25 g/L (Sigma) for 14-37 days. Hepaticdifferentiation may be expected to occur, for example, in a 100%humidified atmosphere of 95% air, 5% CO₂ at 37°, hepatic differentiationmay be detected after 5 weeks.

Differentiated cells, after 14-37 days, assumed a globular shape with aneccentric nucleus. From proliferation to differentiation, these cellshad increased expression of Albumin, Transferrin, Somatostatin,Erytropoietin and Cytochrome P-450 subunit 2e1, similar expression forc-MET/HGF-r (Hepatocyte nuclear factor receptor), Abcg-2, MDR-I(Siddiqui M. M. et al 2004, De Coppi P. et al 2007), and decreasedexpression for cytokeratin-19 (Ck-19) as demonstrated bysemiquantitative rt-PCR.

Cells stained positive for the hepatic epitelial specific cytokeratins8, 18 and 19, in a greater percentage only after differentiation with asmall filamentous organization as shown by immunofluorescence. Cellsexpressed both Hepatocyte nuclear factor 4α and 3β, after Hepaticinduction as shown by immunoblotting. These are important nuclearfactors for the final morphological and functional commitment intohepatic epithelium (Nagy P. et al 1994, Talens-Visconti R. et al 2006).Cells acquired several hepatocytic functions such as the ability tostore glycogen as demonstrated by PAS staining, and to produce albuminand urea as examined by testing the concentration/dose of these factorsin culture supernatants. Specific immunostaining was demonstrated inexperiments where no staining was detected when secondar antibodies wereused as negative controls and HepG2 cells were used as positivecontrols.

Example 7 DPMSC for Replacement Therapy and/or Gene Therapy

An effective amount of the DPMSCs of the present invention are used incell replacement therapy and/or gene therapy to treat or alleviatesymptoms of congenital neurodegenerative disorders or storage disorderssuch as, for instance, mucopolysaccharidosis, leukodystrophies(globoid-cell leukodystrophy, Canavan disease), fucosidosis, GM2gangliosidosis, Niemann-Pick, Sanfilippo syndrome, Wolman disease, andTay Sacks by administering an effective amount of DPMSCs to anindividual in need thereof. They are used to treat or alleviate symptomsof acquired neurodegenerative disorders such as Huntingtons, Parkinsons,Multiple Sclerosis, and Alzheimers. They are also used for traumaticdisorders such as stroke, CNS bleeding, and CNS trauma; for peripheralnervous system disorders such as spinal cord injury or syringomyelia;for retinal disorders such as retinal detachment, macular degenerationand other degenerative retinal disorders, and diabetic retinopathy.

An effective amount of DPMSCs of the present invention are used in cellreplacement therapy and/or gene therapy to treat or alleviate symptomsof several organ diseases. The cells are used to treat or alleviatecongenital liver disorders, for example, storage disorders such asmucopolysaccharidosis, leukodystrophies, GM2 gangliosidosis; increasedbilirubin disorders, for instance Crigler-Najjar syndrome; ammoniadisorders such as inborn errors of the urea-cycle, for instanceOrnithine decarboxylase deficiency, citrullinemia, and argininosuccinicaciduria; inborn errors of amino acids and organic acids such asphenylketoinuria, hereditary tyrosinemia, and Alpha1-antitrypsindeficiency; and coagulation disorders such as factor VIII and IXdeficiency. The cells are used to treat acquired liver disorders due toviral infections. The cells of the present invention are used in ex vivoapplications such as to generate an artificial liver (akin to kidneydialysis), to produce coagulation factors and to produce proteins orenzymes generated by liver epithelium.

The cells of the present invention are used to in cell replacementtherapy and/or gene therapy to treat or alleviate symptoms of biliarydisorders such as biliary cirthosis and biliary atresia.

The cells of the present invention are used to in cell replacementtherapy and/or gene therapy to treat or alleviate symptoms of pancreasdisorders such as pancreatic atresia, pancreas inflammation, andAlpha1-antitrypsin deficiency. Further, as pancreas epithelium are madefrom the cells of the present invention, and as neural cells can bemade, beta-cells can be generated. These cells are used for the therapyof diabetes (subcutaneous implantation or intra-pancreas or intra-liverimplantation.

Further, the cells of the present invention are used to in cellreplacement therapy and/or gene therapy to treat or alleviate symptomsof gut epithelium disorders such as gut atresia, inflammatory boweldisorders, bowel infarcts, and bowel resection.

Moreover, the cells of the present invention are used to in cellreplacement therapy and/or gene therapy to treat or alleviate symptomsof skin disorders such as alopecia, skin defects such as burn wounds,and albinism.

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1. An isolated population of dental pulp marrow similar cells (DPMSC),wherein at least 90% of the cells in the population co-express of eachof the following markers: CD10, CD13, CD29, CD44, CD49a, CD49d, CD59,CD73, CD90, CD105, Oct-4 Isoform A and B, Nanog, Sox-2, and SSEA-4. 2.The population of claim 1 wherein at least 95% of the cells in thepopulation co-express each of the following markers: CD10, CD13, CD29,CD44, CD49a, CD49d, CD59, CD73, CD90, CD105, Oct-4 Isoform A and B,Nanog, Sox-2, and SSEA-4.
 3. The cell population of claim 1 whereinabout 90-99% of the cell population expresses each of the followingmarkers: CD10, CD13, CD29, CD44, CD49a, CD49d, CD59, CD73, CD90, CD105,Oct-4 Isoform A and B, Nanog, Sox-2, and SSEA-4.
 4. The population ofany one of claims 1-3 wherein 0.25-1% of the cells in the populationco-express CD34 and CD45.
 5. The population of any one of claims 1-3wherein the cells of the population co-express mRNA of each of thefollowing: Oct-4 Isoforms A and B, Nanog, Sox-2, SSEA-4, c-Myc, Klf-4,and Rex-1.
 6. The population of any one of claims 1-3 wherein thepopulation has an average doubling rate of about 28-30 hours.
 7. Thepopulation of any one of claims 1-3 wherein the DPMSCs have the capacityto differentiate into one or more of the cell types of ectodermal,endodermal, or mesodermal lineages.
 8. The population of any one ofclaims 1-3 wherein the DPMSCs have the capacity to differentiate into atleast two of the cell types of ectodermal, endodermal, or mesodermallineages.
 9. The population of any one of claims 1-3 wherein the DPMSCshave the capacity to differentiate into all three of the cell types ofectodermal, endodermal, or mesodermal lineages.
 10. The population ofany one of claims 1-3 wherein the DPMSCs are human DPMSCs.
 11. Anisolated population of cells derived from human dental pulp, wherein atleast 90% of the cells in the population co-express each of thefollowing markers: CD10, CD29, CD13, CD44, CD49a, CD49d, CD59, CD73,CDw90, CD105, Oct-4, Nanog, Sox-2, and SSEA-4; wherein 0.25-1% of thecells in the population co-express CD34 and CD45; wherein the cells havenormal karyotype; and wherein the cells of the population have thecapacity to differentiate into cell types of at least two of ectodermal,endodermal, or mesodermal lineages.
 12. The population of any one ofclaim 1-3 or 11 wherein the cells have the capacity to differentiateinto any one or more of the following: osteoblast, skeletal muscle cell,smooth muscle cell, cardiac muscle cell, glial cell, and neuronal cell.13. The population of any one of claim 1-3 or 11 wherein the DPMSCs arederived from a tooth organ.
 14. The cell population of claim 12 whereinthe tooth organ is from a child.
 15. The cell population of claim 12wherein the tooth organ is from an adult.
 16. An isolated population ofcells which has been cultured to induce differentiation wherein thestarting population is DPMSCs of claim 1, wherein the differentiationresults in the DPMSC becoming a differentiated cell selected from agroup consisting of: a bone cell, skeletal muscle cell, smooth musclecell, cardiac muscle cell, glial cell, neuronal cell, skin epithelialcell, liver epithelial cell, pancreas epithelial cell, pancreasendocrine cell, pancreatic islet cell, pancreas exocrine cell, gutepithelium cell, kidney epithelium cell, epidermal associated structure,hair follicles, soft tissues surrounding teeth, dentin (teeth), enamel(teeth), and cement (teeth).
 17. The population of any one of claim 1-3or 11 wherein the genome of the cells in the population has not beenaltered by insertion of pre-selected isolated DNA, by substitution of asegment of the cellular genome with pre-selected isolated DNA, or bydeletion of or inactivation of at least a portion of the cellulargenome.
 18. A method of obtaining a population of DPMSCs of claim 1comprising culturing a dental pulp source in media supplemented withgrowth factors selected from the group consisting of: platelet-derivedgrowth factor, insulin, selenium, epidermial growth factor (EGF),insulin-like growth factor (IGF), dexamethasone, linoleic acid, andascorbic acid to obtain population of DPMSCs of claim
 1. 19. The methodof claim 18 wherein the DPMSCs are human DPMSCs and the dental pulpsource is from a human.
 20. The method of claim 18 wherein adherentcells and non-adherent cells are co-cultured without selection byimmunodepletion, physical depletion, or chemical depletion.
 21. Themethod of claim 20 wherein the method does not deplete the startingsource of cells or the cell culture of mononuclear cells co-expressingCD3, CD14, CD19, CD38, CD66b and CD45⁺ glycophorin A.
 22. The methodclaim 20, further comprising placing the cells in a cell culturecontainer, wherein the cell culture container does not comprise anextracellular matrix (ECM) substrate.
 23. The method of claim 20,wherein serum percentage comprises about 0.5-2.25%.
 24. The method ofclaim 18, wherein the insulin is present at a concentration of about 10to about 50 μg/ml, transferrin at a concentration of greater than 0 butless than about 10 μg/ml, selenium at a concentration of about 0.1 toabout 5 μg/ml, linoleic acid at a concentration of about 0 to about 1μg/m, dexamethasone at a concentration of about 0.005 to 0.15 μM,L-ascorbic acid at a concentration of about 10-50 mg F/L,platelet-derived growth factor at a concentration of about 5 to about 15ng/ml, epidermal growth factor 1 to at a concentration of about 15ng/ml, insulin-like growth factor at a concentration of 1 to about 15ng/ml, and ml and fibroblast growth factor-b1 to at a concentration ofabout 15 ng/ml.
 25. A method of providing therapeutic assistance to anindividual in need thereof comprising administering an amount of DPMSCseffective to aid therapy to the individual.
 26. A population of DPMSCsproduced by the culturing method of any one of claims 18-24.